Splinter Cell: Conviction, Halo 3: ODST, Left 4 Dead 2 and Forza Motorsport 3 so far are Microsoft's first party releases for 2009. That's a pretty strong line up of first party, especially since Halo 3: ODST is the most wanted game out of E3.
3rd party games like Modern Warfare 2 and Beatles Rockband will sell very will, both have some form of exclusive content.
There is also rumors of Microsoft making the Elite the standard 360 in the fall and cutting the premium. They would probably cut the price of the remaining premiums heavily to sell them out, thus boosting the 360 sales.
And then all the things they are doing with LIVE, I think it is possible.








