1. Medicare has no unfunded liability
2. Medicaid has no unfunded liability
3. there is no national debt
4. the budget is currently balanced
5. the budget starting next year will begin to run heavy surpluses.
if those 5 things are true, then yes, we have 25 years. if they aren't true, then our time window get's significantly shorter.
there is a reason the AARP just signaled that they are willing to discuss reductions in Social Security Benefits. Because the math is obvious to anyone who doesn't desperately want it not to be true.