The Brit's future has been the subject of much debate since he won gold as a super-heavyweight at the Olympics in the summer.
Schaefer believes that Joshua's quality and personality could provide him with the platform to succeed in America too.
"Joshua is a terrific fighter," he said. "He is the total package and I think he is going to have an opportunity to eventually become the heavyweight champion of the world.
"We currently have the Klitschko brothers dominating, but in my opinion they are more the champions of Europe.
"They have totally failed to capture the US market and I think Joshua, with his style and personality, has the opportunity to become the standard for boxing."
Joshua has yet to announce any plans to turn professional.