Probably a remaster of FO3 and New Vegas would make the most sense.Holy shit. Not only will they be fast tracking S2, but I'm sure MS is really eager to get another Fallout game ready ASAP — either a remaster or a new game entirely.
It would be pretty cool if Bethesda themselves actually didn't make any game that takes place around the show's setting (LA/Vault 33) but left that open for modders to create their own stories. Similar to the Fallout London mod but with Creation Kit 2.