The 24-year-old has long been linked with a move away from the Trotters.
The former Aston Villa ace has become a member of the England squad.
“There will come a day, and I hope it doesn’t come in January, that Gary Cahill will probably outgrow the football club, given the finance involved in it,” Coyle told the Bolton News.
“I firmly believe that he could play for any of the top four clubs. And if that day comes, then Gary would go with our blessing because he’s been a terrific servant for the football club.
“The reason those clubs are in for him is because he’s been playing consistently well for me as a manager.
“I have always said I have no qualms with anyone, as long as they pour their heart and soul into their job.
“And if that’s the case, then he would go with my blessing.
“He’s different class when he does the simple things well and I think he’ll go on to have a fantastic international career.”
