Arkane Austin's Red Fall was a shitshow, so closing down and moving staff to other studios make some sense. MS wants to get a new Fallout game out ASP and moving staff to Bethesda seems like how they will do it, rather than to outsource it.
Tango closing down is awful, they made the only first party game this gen for MS that everyone seemed to enjoy, and really doesn't help XBOX publishing weak game diversity. I think Tango closing down shows MS's plan for XBOX is big games and GAAS stuff, no small or mid range games.
Wouldn't be shocked if double fine or ninja theory got it next.