I see two possible outcomes.
1) game releases on PS4 eventually as a result of the backlash / poor sales on Xbox One, but sales overall suffer dramatically over what the sales would have been had they just launched multiplat to begin with.
or
2) Microsoft basically paid enough to fund the development and it stays exclusive permanently, and SE react based on sales, if sales are great then Tomb Raider may be okay, if sales reflect that of previous tomb raider titles on the xbox platform, I genuinely can see SE canning crystal dynamics.
Neither outcome is especially great, in my opinion this announcement may have caused irreparable damage to the franchise and to Crystal Dynamics.