You'll still get plenty of real 3rd party exclusives going forward, just not from Microsoft. Sony and Nintendo both fund and assist with the development of games like Journey, Bayonetta 2, and Bloodborne, whereas Microsoft largely allowed their internal development teams to shrink last generation as they moved on to pursue Kinect (and this generation with TV). They just don't have the manpower to do anything except pay third parties to stop developing the already-ongoing multiplatform versions of their games.

That's what the Tomb Raider backlash was about and a big reason why so many 360 owners have switched over to PS4.