Van Nistelrooy expects it will ultimately be the player's decision whether he stays or goes.
"It is a matter of how he feels. If he feels he is committed to the club I think there is an opening," said the Dutchman.
"If he says there isn't I don't think there is a future for him but it is up to him.
"I think the fans would love him to stay but it depends on the commitment.
"If he is fully here everyone loves him but when he is not fully committed it is probably better to move on."