Huth has not played for the first team since suffering a knee injury during the 2-0 win over Sunderland on 23 November which subsequently required an operation.
The German managed to play for 45 minutes in a behind-closed-doors friendly on 25 February but has not returned to the matchday squad and has now missed 20 fixtures in all competitions.
Coates told The Sentinel: "It is my understanding that it is very unlikely he will feature again this season.
"If that is the case, then all the focus now is getting him ready for next season.
"It will be good to have him available again because, along with Ryan Shawcross and Asmir Begovic, he has long been part of the backbone of our team.
"But the fact we have done so well without him is a tribute to the team in general and to Marc Wilson in particular."
Wilson has been lining up in the heart of the defence in the absence of Huth and Stoke are on course for a mid-table finish as they are currently 12th in the standings, six points clear of the drop zone.