Personally, I think it would be ideal if Bethesda continued to work on East Coast while Obsidian works on West Coast (hopefully New Vegas is not the last Fallout spin-off they will make). Both teams have their visions of future and the parts of the world they created probably fit them the best.
While I would like to see how things developed on WC after events of New Vegas, I would also like to see what happened in EC now that the trade has been simulated, BoS has grown in power and the Lone Wanderer brought order to Washington (the Black&White-ness of F3 can be seen as the Lone Wanderer brutally cleansing Washington from bad guys). Who payed the Talon Company to keep Washington in an Anarchy? What will happen with EC BoS now that Enclave has been destroyed and they theoretically control the EC? What about BoS Outcasts? Did the Enclave die and if not, will they stay true to their oldest ideals or will they follow Autumn's ideals?
Since reviving the franchise has been accomplished, I do think Bethesda can now focus more on the story and making it more unique and making good use of it.
Of course, WC also does sound interesting as all endings of New Vegas could change the flow of history there. If NCR won, will they continue with their aggressive expansions or if they lost, how will that affect their territories? If House won, how will he affect the world? What happened to Yes-Man after the reprogramming? What about the Legion, will they still play the role in future and how would Ceasar's death affect them? Have they created Rome in Vegas or somewhere else?