The Republic of Ireland international played much of last term at left back for The Red Devils, but Ferguson is already looking to Argentine international Heinze to take on that role for the coming campaign after signing the South American this summer from Paris Saint Germain.
O'Shea, 23, has travelled with the United squad for their pre-season tour to the United States this week, with Ferguson admitting the young Irishman may have to consider playing in another backline position for the club.
"I've had a few chats with the boy, he knows himself," Ferguson said. "He's still only 23, very young for a defender.
"He has to maybe look at another position. He's a naturally right-footed player and could play centre midfield, centre back or right back maybe.
"He's very versatile, but he's suffered because of that. But he's a good type, and you always think with guys of decent character is that they find their way back.
"He's got years ahead of him."
O'Shea, however, may have a chance to cement his place at right back next month, as Heinze has been chosen as one of three overage players to represent Argentina at next month's Athens Olympics.
Heinze is currently in Peru representing his country at the Copa America and manager Marcelo Bielsa has called Heinze in for the mainly Under-23 competition at the Olympics.
He joins Valencia defender Roberto Ayala and Internazionale winger Kily Gonzalez in being the three overage players in the Argentina Olympic squad, as Ferguson looks to be without his new defender for the start of the new campaign.
United will also be without Cristiano Ronaldo, who was called in to Portugal's Olympic squad for Athens.
