Unfortunately there is a mod for that on PC, but this won't happen on the consoles.
*(I suspect that the end-game story credibility will suffer noticeably with the use of that mod.)
I haven't beat the game yet, but from what I can tell so far, the endings will involve a huge shift in the power balance of the Mojave. It wouldn't make sense to keep playing, unless they completely remade every area, and every piece of dialogue.