In the meantime, the FairTax allows for the entitlements to be funded while doing nothing but keeping the present system is a recipe for disaster as you note. With the FairTax, once the SS/MC laws are revamped the funding will be changed without any alteration in the FairTax so that the newly-reduced entitlements will take effect with no legislative delay beyond revamping the SS/MC laws - those are what govern these entitlements, not the FairTax. Also, the prebate does not go to "every household in Americs" at all.
Lower benefits or higher taxes....its that simple. So what does the FT rate have to be to cover the unfunded liabilities? Also, WHY would you want to PAY for prebate disbursements?