When you consider that the original age of eligibility was basically the same as life expectancy, it wouldn't be crazy for eligibility to be raised to 80. I think that could be done gradually, especially with how they've changed the withdrawal formula to allow early and late withdrawals.

I used to be in favor of means testing, because I thought of it in the same terms as other welfare programs, which is how it's treated by the government. Your point made me think, though, that the current program is a forced loan to the government, whereas means testing would make it outright theft.