Huth has been out of action since injuring his knee against Sunderland on November 23, an injury which subsequently required an operation.
The German featured for 45 minutes in a behind closed door friendly on February 25, but is yet to return to the match day squad and has now missed 20 fixtures in all competitions.
“It is my understanding that it is very unlikely he will feature again this season,” Coates told The 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.
“But the fact we have done so well without him is a tribute to the team in general and to Marc Wilson in particular.”
Marc Wilson has featured prominently as Huth’s replacement, with the Potters likely to finish the season in mid-table.
They currently occupy 12th spot in the Premier League, and sit six points above the drop zone.