The true answers are blindingly obvious. The first is to return to the original Social Security concept, that being as an ADDITION to your own savings for retirement.
Make certain that all the promises for current participants are kept for those of a certain age (fight over what that age should be!) but change the promises for those who are below that age.
Set up a new system which will pay a fixed amount (based on what you put into the system and what interest rates are calculated, as well as for what years the payments were made) for a FIXED period of time (with any remaining amount, should you die earlier, payable to an heir) based on a true actuarial assessment. You, and you alone, would be responsible should you outlive this.