I think Stoner is the only guy capable of getting the most out of that aggressive mapping the Ducati engine seems to have. This sentiment was confirmed by some colleagues who do R&D for the Ducati MotoGP team, and they suggest that the goal this year is to attempt to make the bike more 'rideable' so the teams hopes for a manufacturers title don't ride on one guy's performance.
they are running big bang engine this year (ala Yamaha) instead of their normal screamer engine which basically only a handfull of riders have been able to ride...
I'll say the top 4 guys remain, and toss in Ben every once and a while to mix it up...
but honestly, I think it's going to come down to another 2008 season where it was Rossi vs Stoner...
Lorenzo is out of testing for the rest of the tests and won't have access to Rossi's data/setup
Pedrosa is a front runner with the big boys, but not consistant enough and is basically made of glass
Stoner is the only one that can put up a fight day in and day out... until he gets sick
Rossi is just too consistant...