Robson, on tour with the side, paid tribute to the centre-back, who signed from Leeds United ten years ago.
"He has had a great career with the club," Robson told the club website. "There's no reason why he shouldn't last a lot longer.
"Rio is a naturally fit lad with no weight on him. He's a good athlete. He's been having a few problems with his back but the boss is good in the way he can nurse Rio through that side of it.
"As long as Rio has the desire to want to keep going, there's no reason why he can't play quite a few more years, especially being a centre-half."