The Dutchman, now managing FC Groningen, believes the young Bhoy's form for club and country is catching the eye of clubs all over the world.
Tottenham are already known to be keen on the Parkhead star but Huistra, himself a former winger, insisted to the Daily Express: "There will be plenty more clubs keen on him.
"I watched Forrest play for Scotland Under-21's against Holland in Nijmegen on Monday night and was very impressed. He caused our players a lot of problems with his pace and trickery.
"There were plenty of managers and coaches at that match as well and they will all have gone away with Forrest's name in their books.
"I know, because I still keep in touch with things in Scotland, that he's been doing well for Celtic too and that he's also played for the senior international team a few times so it's clear he has become the most wanted players in the country.
"Celtic have a real asset there but clubs from other leagues will test their resolve sooner rather than later."