No role for him. He is terrible defensively and I don't believe he can score a basket a minute. That's what it would take for him to compensate for his defense. He's Steve Novak.
Yao can create good 3-point shots when he gets the ball. But we all know how hard it is to get him the ball when the other team decides to front. Without Yao, they get more penetration from the guards. They get out more in transition, which is a pretty good way to get good 3-point looks as well.
His last year on his contract is a player option, not a team option. Him picking up his option is a no brainer.