The Manx Terror just won MSR. He bagged 4 TdF stages last year among a bunch of other victories. He's not unbeatable, but no one seems faster than him when he has the correct launch---his finishing speed is excellent.
So . . . what else does he need to do to cement his place in the firmament of sprinters? The remaining items of hardware (as I see them) would be a rainbow jersey, another monument, and a points jersey at the Tour. All of these could prove elusive: Great Britain tends not to have a strong squad at the Worlds, the other monuments don't play to his strengths, and grand tours have not just hills, but mountains.
I think he needs to go after the green jersey next. His new Svengali, Ete, can tell him how it's done, and since apparently just talking to Zabel makes you a better climber, I think he'll have the legs this year.