They aren't Obsidian is. Microsoft owns both and put Obsidian back in the wheelhouse after canceling Obsidians current projects.

As far as a remaster goes that's not a full house affair for Bethesda and they will probably send that to the 76 studio to reskin. They already made a lot of assets that will easily be recycled.

Id wager what will happen with 5 is Obsidian writes it and directs the major story lines while Bethesda provides engine and art support