Here's how you fix it:
1.) You re-tool Medicare to widen its coverage, in preparation for what will actually save it:
2.) You open Medicare to everyone. Until 65, Medicare is a buy-in system. You will actually have to pay for it. Just like you pay for an insurance policy. Actuarially-sound price scales are created, with sliding scales derived from them for income sensitive pricing. Basically Medicare becomes an option on the "Exchanges" that will be up and running beginning in 2014.
And how will this fix Medicare?
1.) A flood of young, healthy people ditch their private insurance for this "public option" that provides better value for the money. Medicare has a 5% overhead rate. The private insurers take something like 30 cents out of every dollar paid in premiums for overhead and promotional costs.
2.) This pool of new, young blood in the Medicare program spreads the risk and re-balances the pool of insured.
3.) This will not harm private insurers one bit: instead of trying to sell people insurance policies they sell people "MediGap" policies that cover the things Medicare won't. Like gynecological and obstetric care, for instance...you can bet this new expanded Medicare will not touch women's health issues...third rail time.
There, fixed it for you.
I'll throw in a bonus: I'll fix Social Security too. Did you know there is a ceiling on income taken by FICA? After a certain point, your income is not subject to FICA taxation. You know how to fix Social Security and not have to worry about it for another century? You remove the ceiling and subject all earnings to FICA taxation. Bada bing bada bang Social Security is solvent. You take that money and put it in that lock box Al Gore was going on about in 2000, so that Republican raiders can't get their grubbies on it. Fixed that for you too.