Warren Buffett isn't going anywhere anytime soon, says former hedge fund manager and Berkshire Hathaway (BRK.A) - Get Report(BRK.B) - Get Report expert Whitney Tilson.

"It's not imminent, I think there is a good chance he is running Berkshire five years from now," Tilson tells TheStreet. "Mentally he has never been better."

That's hard to argue with, to be sure. Buffett, 87, and long-time business partner Charlie Munger, 94, are weeks removed from another masterful performance at Berkshire's annual shareholder meeting. But, Buffett continues to fuel speculation that he is closing in on retirement perhaps sooner than age 92. 

Buffett stepped down from the Kraft Heinz (KHC) - Get Report board in late April, saying he wanted to travel less. 

Earlier this year, Buffett appointed long-time Berkshire executives -- and favorites of his -- Gregory Abel and Ajit Jain to the board as vice chairs. The move was viewed as a signal to the market that Buffett is nearing an exit as CEO.

"It may be Greg Abel, but nobody really knows," Tilson says. 

For now, that successor probably doesn't matter. 

Watch what Tilson thinks about struggling electric car maker Tesla (TSLA) - Get Reporthere.