Interesting that one's powers decline with age..... As if getting old weren't bad enough.
A small percentage of people don't lose their powers, or they might keep them a decade or two beyond the average. Or maybe they lose them earlier. It might depend on the powers.
A-Class heroes keep their powers through they entire lives. Although the last known one died in the 1950s. They are almost god-like in general, and typically live for a few hundred years.