As you may have read, Microsoft has struck a deal to have Tomb Raider exclusive to XBox (timed exclusivity, details are still sketchy)
Should they continue to lag in sales behind PS4, it's not out of the question to have them purchase another established franchise to help them with console sales.
I have made a brief list of those that I believe have a chance to receive Microsoft's financial assistance, while leaving out ones that are unrealistic (CoD, GTA, Assassin's Creed).
My vote goes to Resident Evil, what are your favorites?