I think it falls to which team is going to be able to dedicate themselves to one, and only one, rider for the win on the Via Roma (Though I think the actual finish is a few blocks away again this year).
For the heavy favorites:
LPR: Petacchi has Ongarato, Bernucci, and Bosisio who can be counted on to tow him to the line. The wildcard is DiLuca, who I think won't be able to resist taking a dig on the Poggio.
Liguigas: Bennati should be able to count on Basso, Nibali and Vanotti, with only Pellizotti to possibly take a flyer.
Quickstep: Boonen will have the numbers, and more importantly, the complete dedication of his team, to take the win. Tosatto is always dependable, as is Marco Velo (I'm sure Petacchi wonders how these guys could ever be working for someone else
There's also Chavanel and Davis. Chav, I think, knows and accepts his role in the team. Davis, whom I believe finished 2nd in MSR a few years back, will provide a perfect leadout in the finale.
Of course, there's always Pozatto or Gilbert for a last minute flyer. But I don't think either has Cancellara's raw horsepower to make it stick.
So, I think the photo on the front page of Sundays Gazetta della Sport will be the same as the one from '06, with Petacchi's arms spread wide in disgust at taking 2nd, and Boonens thrust straight in the air, albeit, this time in first. You'll just need to photoshop Pozatto out of the frame entirely.
2 - Petacchi
3 - Husholvd