The 33-year-old has one year remaining on his contract at the bet365 Stadium and made 30 Premier League appearances for the Potters last season, but the arrival of Darren Fletcher from West Bromwich Albion is expected to limit his first-team opportunities.
Championship side Aston Villa have been linked with a move for the Republic of Ireland international, and Coates confirmed that it is a "possibility" the veteran will leave.
"If someone comes in for Glenn and Glenn wants to go we wouldn't want to stand in his way. I don't predict things like that in football but it's a possibility," he told Sky Sports News.
Whelan has spent nine-and-a-half years with Stoke, scoring eight goals in 338 appearances during that time.