So here's an idea: why not reform Medicare by means testing it? Conservatives should love this idea.
Here's how it works. Basically, we leave Medicare alone. Oh, we can still go ahead with some of the obvious reforms. Comparative effectiveness research is a no-brainer for anyone who's not part of the Republican leadership. Ditto for some of the delivery reforms on the table. Or allowing Medicare to negotiate for lower prices. It would be great if that stuff works. But if it doesn't, then people will need to pay more for their care. So why not have dead people pay? They don't need the money any more, after all.
So Medicare stays roughly the same, but every time you receive medical care you also get a bill. You don't have to pay it, though. It's just there for accounting purposes. When you die, the bill gets paid out of your estate. If your estate is small or nonexistent, you've gotten lots of free medical care. If it's large, you'll pay for it all. If you're somewhere in between, you'll end up paying for part of the care you've received.