Both MS and Disney/Marvel know that future MCU movies will need as big a push as possible in transmedia spaces. Gaming-wise Xbox can't provide that push on its own, not the way PlayStation can with IP like Spiderman (and the upcoming Wolverine).
So I think this is a case where regardless what Phil Spencer wants, Disney/Marvel are going to require it be multi-console to help therein give the film (which has a very troubled production history as-is) as much visibility as it can get.
Indiana Jones is effectively a dormant/dead IP film-wise so I don't think Lucasfilm care if a game timed somewhat close to the recent flop is exclusive console-wise to a languishing console platform.
Blade is part of the MCU which is something Disney/Marvel can't afford to have wither away like Star Wars has; they will want any game tied to it to have as much visibility as possible. Xbox can't provide that for them on its own; they need PlayStation to afford that visibility (and preferably, association/crossover with the Spiderman fanbase) to give the film a strong chance at a big box office.
Business 101 suggests it'll be a multi-console game.