But Phelps is limited in his ability to reach the highest levels in the business of sports because swimming is not a popular sport and he only competes on the big stage every four years, compared to professional athletes like Woods or NBA star Lebron James.
"He could become old news because the public won't see him every day -- though Bruce Jenner managed to hang on for a long time," said Andrea Kirby, who was the U.S. Olympic Committee's first media coach in 1996.
"Reggie Jackson once told me about all the attention that Jenner was getting, 'The man's only got one home run. It's only one game. How far can you take that?'" said Kirby.
"As a New York Yankee, Jackson was in the front pages almost every day for most of the year. But as an Olympic star, you're only in the bright lights for a few weeks," Kirby said. "You have to make the stardom last and it's not going to have the same staying power."
The best parallel for Phelps is the career of Lance Armstrong, Shabelman says.
"He was only racing the Tour de France, which only takes place once a year, but Lance was able to find success with endorsement deals -- Nike put him on a pedestal -- and initiatives like his Live Strong Foundation," he said.
It hasn't hurt Armstrong that he regularly makes the gossip columns by dating stars like Kate Hudson and Sheryl Crow, increasing his visibility among the celebrity-hungry public coveted by advertisers.
Phelps may already be on his way in that regard -- he's recently been linked to Olympic record-holding swimmer Amanda Beard, who recently posed nude for an anti-fur ad campaign and in the pages of Playboy, and to British model Lily Donaldson.
"It'll be a good future for Mike," Suttle deadpanned.