You forgot to mention Gears of War as one of this gen's system sellers. Most of the people I know that have 360's bought them solely for Gears. Gears 2 won't be a big system seller though, as 99% of Gears fans already have a 360.
Probably the most ridiculous suggestion, which has been echoed by a lot of people, is that Halo Wars will be a system seller. There are at least 3 reasons why it DEFINITELY will not move systems:
1.) Everybody interested in the Halo franchise bought a 360 when Halo 3 came out.
2.) There is very little crossover between FPS fans and RTS fans.
3.) Strategy games on consoles are always absolute sh*t.
A lot of the others are pretty far-fetched as well: Too Human (development hell), Splinter Cell: Conviction (previous instalments didn't shift xbox), Left 4 Dead (Valve fans prefer PC, 360 FPS saturation); Killzone 2 & LBP may have a slight effect due to all the hype, but it will depend on review scores and word of mouth.