It can be tough to pair dominant big men - there's only so much room in the paint. Ask Detroit, I'm sure they would have preferred to keep Greg Monroe, it just wasn't going to work with him and Drummond.
Especially now when pretty much every team has a small-ball lineup that will ravage any kind of twin tower type pairing. I think if Philly feels like Okafor is the better prospect they will not hesitate to move Noel in favor of a future lottery pick.
But maybe Noel will adapt real well and compliment Okafor defensively. Tough to say until they share the court. In any case, it looks like Okafor is the more talented offensive player, so maybe Noel will be able to focus on defense and tackle the tougher assignment between the 2 of them?