He's never going to break out on Philly. This is a similar situation to what Seguin had in Boston.
Seguin didn't play a style suited to the Boston game. He's a high offensive forward, and the Bruins we're always going to stifle his offensive upside. His offensive style was also just better suited to the center spot than the wing. But you're not going to play him over Krejci/Bergeron. In the end, Seguin was being limited on teh Bruins. That doesn't mean the Bruins are a bad team, just not the right one for Seguin (that deal is a great deal for both teams IMO. Dallas and the Stars got a huge deal).
In much the same way, Couturier is going to be limited in Philly. He's behind Giroux and Vinny right now, and competing with Schenn for that 3rd line spot. Even if he wins, he's not going to put up huge numbers, and his value isn't going to skyrocket. He'd have to outplay Vinny to really get his break and skyrocket his value.
By the end of the 2013/2014 season, I expect one of Schenn or Couturier will be dealt. More than likely I expect one will be dealt by the end of the summer, and it will be for a dman. I suspect it will be Couturier. Luke Schenn played very well for them last year and he's likely considered a long term piece. It's likely they mean to keep Brayden because of that.