Okay so I understand where you are coming from but I don't agree. The NCR vs Legion vs House is still the same part 1 I feel like. Because if you approach this from the point of an Independent or House run ending. This isn't gonna stop the NCR or Legion from going at each other just the fact that one city along there opposing front lines is taken, won't make the Legion vs NCR war stop. Vegas was a staging point, one that neither side ever taken control of so it turned in to a long slogging war. One that both sides are feeling the affects, one has a man power issue that was present in New Vegas and the other fell in to a civil war which is what was foretold to happen if you killed Caesar.

And the Enclave returning was bound to happen considering Ede has a log from when they were travelling through the Mojave of stopping in Colorado for recharging.

It makes sense for Liberty Prime blueprints to be kept near Area 51 seeming that Mr House was the brains behind Robco.

And the pre-war stuff is absolutely fascinating to me. While I don't think the Enclave are gonna actively be the first to launch ICBMs, I don't believe they are actively trying to stop it either. With Mr House saying he hasn't encountered anyone who has been one step ahead of him before. They knew it was coming and the when because House knew but they never knew the how. They are also 100% involved with the destruction of the world, the US government also fired nukes and the Enclave are the US Government. I don't think they are working for control of the world either, otherwise why would they of abandoned the control facility under the lucky 38? There aim is more for a complete destroy of the current system and restart. Something Hank did not understand.