For example, could you say
"You pay 10% of your salary and we'll match that, into an investment account that buys inflation protected treasuries, then when you reach the age of 55 you have the choice of getting 20%, 50% or 100% of your salary paid out annually until the total of the amount paid in + appreciation over that time reaches zero."
Basically once the company/state had matched the 10% they have no further obligation. And if you're genetics were great and you lived to 115 perhaps your 'salary' would run out at 75 long before you died. But what I don't know is how practical this is, it was so much easier when people actually died around 72 than it is now.