The Bosnia international was linked with a number of teams across Europe over the summer, including Arsenal, Chelsea and Napoli.
Despite Begovic's decision to stay at the Britannia Stadium, Coates admits that there is likely to be renewed interest in the keeper.
"You always have to be realistic about these things," he told The Sentinel.
"If a call came from a top European club and was attractive to him, then you have to look at it.
"It wouldn't be much of a surprise to me and that's why we have contingency plans in place with other goalkeepers at the club."
Begovic joined Stoke from Portsmouth in 2010.