His chances are always going to be limited when he's on the same team as an in-form Boonen.
There are really only two circumstances where he could realistically be given the opportunity to ride for himself: Boonen picking up an injury, or a situation where he covers an attack for Boonen and that attack goes to the end. And the chances of the latter happening are limited by his own abilities - other teams are going to be pretty reluctant to let him get too far up the road.
You can't really make much of a case for him being allowed much in the way of his own opportunities when the team are winning race after race with him working for Boonen. On the other hand, if Boonen gets injured in training, Chavanel will find himself as the main leader of the strongest Classics team.
On balance, unless OPQS are paying him way over the odds, he'd probably be better off elsewhere. He'd be the main cobbled Classics leader of any team other than OPQS, RSNT or BMC.