We are Talking about exclusives. the customer does not care if the game he wants to play is a 3rd or a 1st party exclusive!
I said it some weeks ago and I will repeat it right now. MS will go to 3rd party developers (like Bethesda as an example) and say: "develop a game for the Xbox360, here are 15 million USD, additionally you will get 3USD for every game sold. The franchise belongs to us" Bethesda will be fine with that, I guess. MS will do the same with a lot of other developers out there. Square Enix (Infinite Undiscovery) was just the beginning. This is MUCH more efficient than running your own 1st party studios.
Killzone 2 was in development for more than 4 years. Running a studio for 4 years and paying everybody working there from the head-designer to the doorman is not cheap. Of course the studio / Sony has not seen one cent of revenue for 4 years.
Pretty much the same with GT5. But GT5:p created some revenue.
And as soon as MS thinks they don't have not enough exclusive content, they simply make orders for exclusive games, like I described earlier. That is much cheaper and faster than starting a studio, looking for good developers, pay them (maybe buy them from other developers), get the facility etc.
Imagine not having GamePass on your console...
