If Microsoft wants to use cloud-computing they should have just required a strong broadband connection before buying the console. Imagine games suddenly requiring that and thousands of players around the world buying games they can't play. Either lawsuits or just an abrupt loss in games sales from then on in those places.
It is just not feasible and no multi-platform game will take advantage of that. If Microsoft uses cloud-computing for exclusives they will be alienating a really big audience with bad connections (who unknowingly bought the console, since it isn't required).
Another horrific scenario would be Microsoft's attempt to let people with a bad internet connection be able to still play the game. It would have to be however, a lower res, lower framerate game, just to try and say they got everyone covered. If they bought the same console as everyone else, but have to play lesser games that is really unfair (and flat out wrong).
I for one live in an apartment in the capital and my internet connection is absolutely abysmal. I try to change it, but I merely pay the rent, cannot afford much better and the owner of the place wouldn't even let me. Cloud-computing is impossible for me at this stage.