Huth's last appearance for Stoke came in the 2-0 win over Sunderland in November, but he limped out of that game in the 77th minute with a knee ligament injury
The 29-year-old looked close to a return last month after featuring in a friendly, but Coates now believes that he will miss the final nine games of the Premier League season.
"It is my understanding that it is very unlikely he will feature again this season," he told the Stoke Sentinel.
"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."
Huth has made over 30 league appearances in each of the past four season for Stoke, however he has been limited to just 12 so far this term.
