Quite frankly, I don't know where Doom's next direction is after this. Doom Guy already killed the equivalent of God and now we have this neo-Quake like prequel. Is he, if ever he wakes up again, going to other worlds and do monster-killing all over again after killing a god of creation?
I can see it continuing, I wanted the third game to be a sequel but that's likely not going to happen. Maybe, just maybe Doom 4 if they even get to that point can still be one. Regardless, there are still tons of unanswered questions and plot threads (granted, these should've been answered but whatevs)
1. Samur was pretty much fully transfigured by the end of TAG1 and we've been told all game how that leads to insanity. There's also still the Demonic crucible in existence so even if all the portals to Hell have been closed there's still some form of its influence existing on the other side. By that alone you already have your villain and reason for demons showing up outside of Hell, or maybe they can go full Doom 64 and have it be set mostly or entirely in Hell. I kinda like the idea, the stories have already been retellings of the past games anyways.
2. The fate of the Father. I could see him being a side-antagonist or just having the same role of being an observer to the games events
3. The fate of the Intern. Maybe a replacement for VEGA. I'm able to stand him in TAG 1&2, but I don't know if I could do a whole game. Also there's something fishy about him, I swear he's the Wretch they talked about in 2016.
4. The fate of the Sentinels.
5. The truth behind the Wraiths and the universe, despite what Davoth says there were clearly some other things at play before his time. He's also the devil, so why should we believe anything he says about him "creating" the world?
6. How does Doom 3 fit into this? (God please don't answer this one. Have it stay separate)
7. (my biggest one) There is still no real "good" afterlife in this multiverse. Since some form of salvation doesn't exist (Religion is implied to be misinterpretation of Makyr lore) all sentient life seem to go to Hell by default. Obviously we can kill demons all we want but that still means their numbers will still replenish as shown in Eternal. In fact you can even go so far as to say that the Slayer is an antagonist as it was efforts in 2016 that lead to Earth being invaded since the Well was destroyed by him. Thus he pretty much damned most of his own people to Hell and now he has to kill all of them. My solution? Destroy Hell entirely, like completely finding a way to remove it from existence and become God and establish something better. Or pretty much just what Thanos had in mind at the end of Endgame.
Yes I just made a MCU reference, I couldn't think of anything better to use
8. Some of the prophecies of the
Whispering Tree from the Kadingir Sanctum in 2016 have still been unfulfilled.
"Could he be demon kin, spawned from the loin of a grotesque infidel? Yet, the seal of the heretic binds him. His origin is as dark as his coming."
Answered in Eternal, The Slayer was a normal human (Doom 1-64) and got sent to the Nu-doom universe and the rest is history
"The power held within the Crucible will punish man-born and demon kin alike. It will crush the divide. It will corrupt all realms. It will create the monster. It must never be found."
Somewhat unanswered, what is the monster they speak of? What of the divide being crushed? Perhaps the Crucible can be used rebind the barrier created by the end of TAG 2 or even merge Hell and the multiverse together?
"The heretic-turned-apostle Olivia, birthed of the dawn of our resurrection, by her hand we cross the divide. And for her tribute, she shall be granted the form of the Dread Widow."
Answered in 2016, pretty clear what it means. No idea what "birthed of the dawn of our resurrection" means. Maybe its meta in the sense that 2016 is a reboot?
Yet even as the Doom Slayer revels in the spoils of his war, another shall rise from the fires: a dark priest consumed by the Crucible. And even the Doom Slayer shall weep in his shadow."
This is the one that I'm really sad may never be revealed. I know most of these are flavor text or have been pretty much retconned but still. The dark priest could easily be Samur and I can see him immediately going after the Crucible in his madness post-TAG2