You make it seems like they magically will just stop working with other parties to develop their IP when they really have shown no hint of that.
We still have Undead Labs's Class4, Scalebound, Crackdown, a game with Skybox Labs, as announced titles for "beyond". Not to mention Gigantic but I think that will be out this year if Motiga survives. As for MS studios I'm expecting another Forza next year and possibly something else from Rare. They also have Decisive Games working on a strategy game.
What if they show you a few more between this E3 and Gamescom? What's saying they can't do that?
You make it seem all doom and gloom for really no basis other than, they only own 6 internal studios and closed down Lionhead! MSs strategy has been to work with outside Devs on IP MS owns so I'm not sure why all of a sudden there's some huge concern.
Not doom and gloom buddy, just being realistic. In fact, the ultimate path I see them taking is PC exclusive and I'm more than fine with that.
Yes there will be another Forza. You think there will be another Rare game? That'd be nice, go look at their output the last 5 years tho, I think you're aiming very high on that one. I used to have high hopes on Microsofts unannounced/new studios but they've literally produced nothing. So until Decisive games come out with something you really shouldn't bullet point them. Same as Skybox lab. In fact, I think I've seen that name floating about for years.
They used to have a lot more first party studios, still do the second party projects and buy out third party exclusives, 360's library was vibrant and alive year in year out (save for the latter years) and even XB1's early years showed amazing promise with their first party and the partnerships.
If you can't see the massive decline that's your own problem, like I said. This time last year we knew of about 10+ exclusives coming in 2016 and beyond. This year? Just Scalebond, and the obvious Forza.