Understand that medicare and medicaid are currently funded almost entirely out of general revenue from the income tax. The tiny 2.9% payroll tax dedicated to it does not remotely cover its outlays. For social security, the amounts being collected right now do exceed those outlays, and will for something like another 10 years. Neither is actuarially sound, in the insurance sense of collecting as much in premiums as is promised in benefits, the time value of money (interest) taken into account.
The unfunded liability calculation is basically the amount of ongoing general tax revenue required to pay for them, divided by the current interest rate. Mathematically speaking that looks larger when interest rates are low.
It is not much more than a pious wish that we had that much extra capital. The actuarial reality is that health costs cannot continue to grow that fast and be paid for with a blank check, nor can low retirement ages and higher than inflation COLAs be granted to every future retiree when there are twice as many of them per worker, without each such worker paying more in taxes.
It is obvious to me what the conservative solution to that issue is. Gradually raise the retirement age, slow COLAs to inflation (right now they are pegged to wage growth, which is as much faster as real economic growth and makes it impossible for the real economy to catch up), transition medicare to a catastrophic insurance only level of coverage, and provide full coverage only to a means-tested subset of Americans who can't afford private insurance plans. Also allow existing workers to contribute a portion of their current SS premiums to private accounts of real funded money that they own, and gradually raise the portion so allowed.
The reason to do all of those things is because middle class Americans can stand on their own two feet, income from real capital can fund costs better than taxation ever can in efficiency terms, and the only way to control cost growth is to stop subsidizing sectors with galloping prices. The obligations that younger generations have toward older ones should be met by the former passing on their accumulate wealth to the latter, voluntarily and by private means, and the government should get out of the business of standing in between them and lying to both sides. Not because we don't own everything, we do. It is just the honest, straightforward, businesslike way to handle pensions and health care.
This seems like a good plan to me!