But he warned the defender that he faces year-to-year contracts from next season.
Ferguson told the Daily Mail: "At his age it would be a one-year contract extension. As a centre back, if you stay fit and look after yourself you should be playing until your 37. As long as he manages himself properly he can do that.
"I think he’s doing his yoga and that helps. He had a terrific season. He probably played his best football for us for a long time because he was playing quite regularly.
"The last two years he’d been playing for a week, out three weeks, then coming back. Rio and Jonny Evans hit a bit of form together, that carried from December right through to February and March. He played three games in seven days, when we played Bilbao in the Europa League, and got through it."