IMO we need two additional stars to be contenders.
Ibaka might have qualified as one, but we'd need to also add a better star. Problem is, if we make a trade for him with an expiring like Amir, we need to resign Ibaka in fee agency at a huge deal that not only eliminates our ~$30M cap space in free agency, but likely puts us over the cap.
So that takes us out of free agency, and we're overpaying Ibaka.
But if we let those contracts expire naturally, we can sign a near-max guy in FA and THEN use our other contracts (Bradley Crowder etc) to land the big fish via trade, even if we're near or over the cap.
Free agency needs to come first, and I don't know that Ibaka is the right target there. We can always land a player in a trade ta any time, but once that cap space is gone, free agency becomes impossible.