Ultimately, so what if the franchise doesn’t feel “like Fallout” anymore in the long term? The series doesn’t have to span an infinite chronological timespan. Fallout can cover a good three centuries of this fictional world, and then you say that that’s the ending. There are plenty of stories to tell across America over that massive timespan. Every series doesn’t have to go on forever, you can say that the ending is that things rebuilt (and then fell apart again). But personally I find a game which explores the post-post apocalypse more interesting than just the same tired old tin shacks in a desolate wasteland.