I don't know what it'll be, but I will guarantee that it'll be buggier than a San Fransisco bathhouse and Bugthesda Suckworks will refuse to fix the bugs almost three years after release, and instead spend their time filling your HD with gigabytes of content you don't need or want.
Sorry, had to vent.
It's funny you say that.
I just installed Commonwealth Cleanup, a mod that breaks the Precombined meshes (and has optimized replacements) system so people who want to rip down and rebuild the entire game world can go nuts, and combined with a few other mods I added so I can build anywhere and place stuff where I please, I've been going batshit on Fallout 4's game world, and holy shit, Bethseda is lazy.
Half the reason they went insane with all the fake looking piles of trash was basically to cover up a shitload of game seams. The reason the downtown area is so fucking slow even on beefy computers is because over half the stock game meshes (even with preculling to hide all the shit you can't see) are so badly optimized your processor is shitting the bed rendering assloads of unneeded polygons.
They also did this to disguise the fact they were too lazy to line up static objects that "shimmer" (caused by the two surfaces of a static object overlapping partially), and even though they covered a lot of these, they are still all over the stock game world (check most of the rooftops in Lexington for example), even in many areas a player will find and walk on.
They also were too stupid to marry light sources to the objects that generate them (some even use illuminated statics to do like the emergency lights), meaning if a player clears them from a settlement, they will get weird luminous areas because the light radius still exists minus the light source.
I could go on, but I find it sad that I can rip down any random map and find all sorts of places where they cut corners.
I found similar issues on Fallout 3 and New Vegas (though I can kinda forgive Obsidian, they had only 18 months and had to basically learn as they went along) too.
tl;dr: If we get a new Fallout and it has the same designers who did the previous ones, I fully expect to find more lazy game world design.
