One question for those not interested in this slapfight: why is it that the hardcore Fallout 1 and 2 fans forgive its flaws but then crucify 3 for having the same flaws? I mean, they criticize FO3 for the insanely evil choice of blowing up Megaton, yet killing children in Fallout 1 and 2 isn't just as bad? At least the former gives you a nice nuclear explosion instead of the simple ugly sight of your avatar killing children. Not to mention they crucify Fallout 3 for not letting you join the Enclave, and yet FO2 didn't let you join them either, even though you could infiltrate them to the point where everyone from common drill sergeants and comm officers to their PRESIDENT believes you to be one of them. At least in FO3, the president is merely a propaganda guy with little power of his own, and the Enclave military leader knows who you are and wants your head on a pike, so that justifies fighting them to the last.
How come FO2 AND FO1 don't even give you the option of an alternate ending to the main quest (nonstandard cutscenes where you don't get to play as a Super Mutant don't count) and yet they blast FO3 for having the same? They curse FO3 for making it easy for you to talk down President Eden, yet you can't even talk down President Richardson in FO2, even if you're a seductive porn queen who dumped all their points in persuasion stats. It should be easy to convince Richardson that he's wrong, especially since if 1000 people on an oil rig (and a few hundred on Navarro) inherit the earth, it would only take a few generations before they die off from inbreeding. It should be easier to talk Richardson down when compared to Eden, the Master, or Lanius, since out of all the villains, Richardson's plan is the one that made the least amount of sense.
Then the hardcore fans whine about how the Enclave is just plain evil in FO3, yet in FO2, they're even worse, since in the west coast, the mutants are mostly dispelled, and the Enclave has the firepower necessary to bring the NCR and the Brotherhood to heel, yet they opt for genocide via the FEV anyways, whereas in FO3, it's clearly explained by Eden that he wants to commit genocide with the FEV because his men AND the Brotherhood can't stop the Super Mutant threat, so it's a case of desperation instead of just pointless spite. That, and nobody in the Enclave wants to do it, hence why Eden has to recruit some random nobody to plug the FEV in, making them less genocidal than the previous version of the Enclave which was willing to genocide the wasteland just because they weren't "pure humans." Which, of course, is bullshit, since we see the Enclave in FO2 slaughtering pure humans in the intro. For people who want pure humanity to make a comeback, they're doing an awfully good job and killing said pure humans instead of rescuing them from the wasteland.
Ironically enough, the more positive characterization of the Enclave characters in Fallout: New Vegas came from Fallout 3. Augustus Autumn and his men just want to restore order to the wasteland, hence why they're seizing the water purifier to use it as a bargaining chip, and the NV Enclave mostly has similar goals, with the lead officer in charge even saying that they were just trying to civilize the wasteland and they couldn't care less for the genocidal aims of their superiors. That's a far cry from Fallout 2 where most of the Enclave are portrayed to be dumb followers of a genocidal government that couldn't care less if 99% of the people outside die.
And yes, all these complaints are coming from someone who came in first through New Vegas, which is still, in my eyes, the best Fallout game. FO3 was somewhat enjoyable for me, but between the outdated UI and the underwhelming ways the story ends in the first two Fallouts, I can't understand why the hardcore fans treat FO1 and 2 like they're the best thing since sliced bread, yet have such vitriol for Fallout 3.
The Legion is still a problem but it isn't an immediate one. It took them years to rebuild, strengthen, and come back at the NCR the first time and this time their future is shaky with the loss of Caesar and his chosen successor. Some characters speculate that Caesar's Legion without Caesar ceases to exist and that's before you remove Lanius from the picture. Assuming they have no issues with succession and civil strife over it I think the new Caesar might feel more comfortable with expanding in other directions rather then head right back to the site of two disastrous defeats and force a conflict that if lost could end their reign if not the Legion itself. Lanius thought the campaign was a bad idea from the start and only went along with it because Caesar ordered it. Its my belief its going to be a decade plus before the Legion turns its sights back to the west.
The Mojave Brotherhood is done if you blow up their bunker, their ending says three things happened to its members. They are either killed in the explosion, left the Brotherhood to pursue new lives, or went west to find another chapter to join. The NCR turns its attentions on those that allied themselves themselves with the Legion, especially the Khans. The Khans that didn't die at the dam get driven out of the Mojave all the way into Idaho. The Fiends are still a threat after attacking McCarran and being repulsed but that's all their ending says if you leave all the leaders alive. If you kill a single leader the NCR is able to finish off the rest of the fiends. Either way they lose their primary source of chems which will put a damper on their party going forward. The Powder Gangers in the NCRCF are also executed by NCR soldiers in the ending where you don't kill Eddie but the NCR wins so they are off the table. Cooke's gang continue to be a threat wrecking havoc on the citizens of the Mojave especially the NCR ones. The Boomers stop the NCR from messing with them through the use of their artillery but eventually come to depend on the gun runners for munitions in exchange for crops, assuming you don't get them their plane. The Kings get gunned down by an NCR platoon. The factions the Frumentarii can influence are limited now and that's assuming any are crazy enough to look at what happened to the Khans and still think its a good idea to take the side of back to back losers against the NCR.
The NCR in the west has had those same exact problems before, during, and after the expedition to the Mojave. During that entire time they never stop sending men and resources over the border to help the NCR expand its influence in the region. The NCR negotiates the annexation of Vegas and its surrounding communities shortly after the battle. There is no longer a divide between domestic problems and problems abroad because the Mojave is now New California. The financial burden of Mojave peacekeeping is fundable directly from all new tax revenue coming in from all the communities and casinos they now own. The wealth of Vegas, the power of the dam, the water from lake mead, its all theirs for the taking now. Taxes and levies can be lowered with the immediate threat of the Legion gone and most of the powers that be in the Mojave swept aside.
Kimball no doubt gives some big speech in front of "mission accomplished" banner and your average NCR citizen applauds and goes back to their lives ignoring all the details coming out of the Mojave. All its struggles and fatalities become another normal state statistic as life continues to stagnate in the NCR.
This is how I read the outcome of the bare minimum results going off ending slides if you do Eureka. The NCR finally shows itself capable of removing several of the factions hostile to them, annexes the Mojave, and many of the small communities live safer but taxed lives in the aftermath.
The biggest open question is what happens to the Legion in defeat since there are no slides for that.
The Frumentarii can influence more factions than you think. For example, the New Vegas Three Families. Or the local communities like Goodsprings. They wouldn't be so happy to get taxed to support an NCR occupation of the area, and would be susceptible to subversion by Frumentarii spies and agents. The Omertas were already subverted before. How much would it take to turn the White Gloves and Chairmen, who already don't like the NCR, against them? Not to mention many local communities like Goodsprings won't like the taxation while raiders and monsters continue to plague them. And unlike the Legion or the Securitrons, the NCR usually doesn't protect local areas, focusing more on big-name areas like say, Outer Vegas or the Strip. Unless the Courier went the extra mile to genocide all possible threats like the Powder Gangers and the Fiends, those guys will still be harassing NCR citizens and Mojave denizens.
And again, moving more troops from California to the Mojave would make things easier for raider tribes back in California as well as the Lost Hills Brotherhood of Steel to organize a counterattack against the NCR. Remember when Chief Hanlon stated that some power-armored troops stayed behind to protect Brahmin Baron lands? If those troops were sent east as part of the occupation force, and they most likely will be, the raiders will have an easier time. Not to mention the fact that the California Brotherhood still maintains a substantial military force of heavily-armored and armed troops that can and will cause more problems the moment more troops are sent to the Mojave. Which means that even if the NCR occupation of the Mojave goes off without a hitch, their status back in California will become more questionable, at best.
This, of course, will put a massive dent on the morale of NCR troops. Just as Bush's "mission accomplished" speech ended with him getting shitcanned by the public years later, so too will Kimball's speech be met with derision by NCR citizens who would suffer more raids in California the moment their people back home get attacked by raiders and Brotherhood Paladins. It will lead to less support for the Mojave Occupation Force and maybe even lead to the NCR retreating from the Mojave to deal with the intruders, all the while, the Frumentarii and whatever allies they've scraped up from the Mojave start harassing the NCR. By the time the raiders and BoS become enough of a threat that the NCR brings troops back from the Mojave, the Legion would have rebuilt its strength, and it would lead to a third invasion of the Mojave by the Legion just as NCR troops are being pulled back to defend their mother country.