A couple days back, Ezra Klein took on the big entitlements one by one and reviews tax reform options. He claims there isn't much more we can do to Medicare:
The reality is that most of the best ideas for slowing the rate of cost growth in Medicare -- and using Medicare to slow the rate of cost growth in the health-care system as a whole -- are in the Affordable Care Act. Bundling care? It's in the law. Accountable Care Organizations? Yep. An independent board staffed by experts and able to make cost-savings changes to the system even if Congress gridlocks? Uh huh. An institute dedicated to funding promising new pilot programs, gathering evidence and then quickly ramping up the ones that work? That's in there, too. You could think of some further tweaks and technical changes, of course, and I hope Congress does. But short of privatizing the system and saving money by giving seniors checks that don't cover their health insurance -- a play that some Republicans like, but that I'd be surprised to see leadership endorse -- most of what we think might work is already being tried. The low-hanging fruit has been picked, and so has the medium-hanging fruit.