The Welsh midfielder, who turns 40 later this year, will not be hanging up the boots at the end of the current season and could even go another after that according to Ferguson.
"Ryan is an exceptional human being," Ferguson told Sirius XM.
"He has never carried any weight, has never suffered a serious injury and never misses a training session. He is still at the head of the pack during pre-season.
"He just has this insatiable appetite to continue playing.
"He will play next year and who knows he could possibly play for another year after that.
"I am sure he will get to 41 and still be playing because he is such a fit lad."