I think that's great situation with Yao, for he does have a say here. Given the circumstances, if he's traded, he will be going to some place he sees benefiting him.
Of course, once he extends the contract, sign the next big one. They can send him anywhere they want to. If he's sent to a garbage team, Yao is such a hard worker, he won't be slacking off. That would be sad sad thing for him and his fans.