It would seem that Iverson will be on the squad next year, filling at least the 3rd center spot, and might earn backup minutes.
With Joel Anthony already on board for next season as 3rd string center, I think C.Iverson should stay in Europe for another season.
I've watched Iverson on a couple of occasions this season. I agree that with Anthony on the roster (very similar skill set), Fav (more upside) under contract and trade assets/draft picks for a starter caliber center, staying in Europe is the better alternative.
That said, if the Cs could somehow facilitate a contract in another league - Liga ACB or the Russian league that would be good for his development. Not that these are significantly better overall than the Turkish. It is just less small ball and closer to the NBA environment for a big man.