I talked about the experience Philly had playing Noel and Okafor together at the 4-5 in another post. It was a failure, especially for Okafor, whose production went down, especially rebounds, at the expense of Noel. It led Philly to consider trading one or the other (probably Okafor) at the trade deadline last season, but they held back reportedly due to concerns about Embiid.
The suitor at that time was rumored to be Ainge, who said he was involved in serious talks about a surprise player.
I don't know which of these two Ainge prefers, but I don't think he wants both, based on Philly's experience playing them both together. He does need some offense up front, and Okafor would provide that. He has the size to play inside, and could evolve into a decent rim protector. He has the extension to block shots.
Philly has a problem in that Hinkie drafted three 5s who can only play the 5, as they have learned. Hard to vision Embiid playing the 4. Regardless of Embiid, they still have to deal one of the other two. And if Embiid is healthy, they'll still have a problem of at least two 5s.
Such is the folly of drafting centers three years in a row. Which is why Hinkie is no longer GM.
I would be shocked if Smart is put in any deal short of Cousins.