Warren Buffett is one of the greatest investors ever. But as he grows older, many people worry that he could lose his advantage. Even as Buffett hasn't seemed fearful of his own mortality, there's one regret beyond the obvious that he probably has about not being young.

In the following video, Dan Caplinger, The Motley Fool's director of investment planning, notes that the real calamity is that Buffett has set up so many investments that won't truly pan out until long after his death. In his investment portfolio, well-run companies Wells Fargo (NYSE:WFC), Costco (NASDAQ:COST), and Nike (NYSE:NKE) have competitive advantages that could lose for decades. Moreover, Buffett's wholly owned businesses can take even longer to realize their full potential. More time would give Buffett the chance to see those investments through -- but then it would also just give him other regrets when he made the inevitable new investments to add to them.