The 47-year-old lost his WBC strap to Chad Dawson at the weekend but has refused to hang up his gloves just yet.
Schaefer still believes that The Execution is one of the biggest names in the division and said that a bout with the unbeaten Welshman would be a huge box office draw.
"I could see him, for example, challenging for the WBO world title against Nathan Cleverly," Schaefer told BoxingScene.com. "There are many possibilities, but really, at the end of the day, it's his decision and he's going to have to decide what he wants to do.
"But the fact is he still is the biggest name in the light-heavyweight division."
Hopkins lost to Cleverly's former stablemate Joe Calzaghe in Las Vegas in 2008.