The former Red Devil believes that the 27-year-old will be seen as dispensable if he does not return to his "best condition", with the power in David Moyes's hands
Now-retired boss Sir Alex Ferguson confirmed at the end of the season that the England forward had submitted a transfer request, with Arsenal and Chelsea among the teams interested in offering him an exit.
But Macari told talkSPORT: "I don't know what there is to discuss. Speculation at this time of the year is what we expect but that's not to say that Wayne is going to be leaving Old Trafford.
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"You have to fight to get back to your very best and we all know how good Wayne can be, his Premier League goalscoring record is up there with the best of them and he's guaranteed to score you goals.
"I think United would want to keep a fit and happy Wayne Rooney in his best condition but that's the big question: Is he in his best condition and the right frame of mind and does he want to get back to the form he showed when he first arrived at the club?
"I think the power is with [new manager] David Moyes now. I don't think he'll be that desperate to keep Rooney if he’s not willing to get back into the right condition.
"Moyes is an experienced manager and knows players have to be focused on the job and be fully committed. No matter who you are, if you're not in the right frame of mind you're not going to be staying at Old Trafford.
"I think it depends on Moyes and Rooney sitting down and, if they do, the assurances will have to come from Wayne that he’ll get back to his best, otherwise he might continue to be second best to Robin van Persie."