He told the Daily Record: "Craig will enjoy his time under Roy because he's a good guy and a quality manager as well. If Sunderland progress, Craig will progress with them and you can never say never in football.
"Craig is undoubtedly a top-class keeper and, as things pan out, he might get a move to a bigger and better club in England.
"That all depends on how well Sunderland do. If his form his good and he keeps progressing and he's happy then maybe one of the big teams will take him."
Fletcher has played with Gordon long enough to know becoming the most expensive Scottish player won't faze the level-headed 24-year-old.
In fact, Fletcher can see similarities between the former Tynecastle ace and Old Trafford No.1 Edwin van der Sar.
He said: "I don't think the price tag will bother Craig. He's got no control over that. His job is just to go out and play and it's up to the clubs to agree a fee.
"But he's a talented keeper. I've played with him a lot for Scotland and he's a calming influence.
"He actually reminds me a bit of Edwin. Sometimes people say keepers can be a bit erratic and they should be mad.
"But he's not one of them. He's cool, calm and collected.
"He's got a great future and he is under a great manager in Roy.
"I'm sure he'll be excited about it and I think he will be a big hit."