this might be a turning point, but even as a big Sony fan I can tell you things are gonna turn again when Halo3 comes out. Surely the 360 will outsell the PS3 this Fall because of Halo. However, I think you're right that Halo's gonna be a disappointment to many. The biggest reason why is that the hype for this game has been too huge for too long. Especially with all the Halo gear and paraphernalia and special edition products. On top of that, the competition in the genre is so much better now than when even Halo 2 came out just a few years ago. There's Gears, Bioshock, Resistance, etc. Somehow I doubt Halo's gonna be as far ahead of its competition as it was years ago. Lack of online co-op, which is somewhat of an expectation for such a high profile game, is definitely gonna be icing on the disappointment cake. I think with the release of Halo 3, the first person shooter genre as a whole is going to begin to lose its prominence among gamers and media alike (although this a topic for a whole other thread).
I'm also getting a sense that MS's library next year isn't gonna be able to continue to be as good as it is this year. At least that's the impression I got from E3 this year (No '08 games were shown). Plus, if there ever was a time to trounce Sony in sales, now would be it. Sony's price is as high as it'll ever be, and its library is as weak as it'll ever be. If MS doesn't drop the price, and/or Sony continues to outsell the 360 now when it's so weak, what's gonna happen when Sony's big hitters step up to the plate?
My Top 5:
Shadow of the Colossus, Metal Gear Solid 3, Shenmue, Skies of Arcadia, Chrono Trigger
My 2 nex-gen systems: PS3 
and Wii 
Prediction Aug '08: We see the PSP2 released fall '09. Graphically, it's basically the same as the current system. UMD drive ditched and replaced by 4-8gb on board flash memory. Other upgrades: 2nd analog nub, touchscreen, blutooth, motion sensor. Design: Flip-style or slider. Size: Think Iphone. Cost: $199. Will be profitable on day 1.
