And speaking of DLC, they could also finish side quests with disappointing open ends, like the one with Peralez or Gary the prophet...
Those quests are connected though? Gary gets kidnapped by the blue eyed people at the end of his quest and Mr blue eyes is behind the peralez brainwashing and both quest are connected to the plot about AI which I think will be the main plot of one of the expansions.
Here is all the stuff connected to the whole conspiracy going on in the background of the game.
There is also a question what will Alt do now since in every ending but the Arasaka one she merges with all the constructs stored by Arasaka meaning she gets expierience and knowledge of the most influential people in the world.
I would assume that you don't play V anymore in any sequel. But they could actually continue where each ending left off, like in Tucson or at the orbital heist, in upcoming DLCs or expansions
They can just do what they did with lifepaths and converge all the endings into one storyline after 30 mins of intro. Example Panam said they have contacts that can help V in Arizona and that contact would be Mr. Blue eyes. In the afterlife legend ending you meet Mr blue eyes and work for him directly. If johnny takes the body he can come back with the promise of bringing V back from Mr blue eyes etc.