The price of dealing with an extremist opposition?

There is a meme gathering steam on the left -- whether triggered by Ezra Klein or by multiple people in the know or making the same deduction -- that Obama will accede to raising the Medicare eligibility age as the price for pretty much getting his way on taxes (and stimulus)?  Here's how Don Taylor compressed the logic in a tweet: 

it is only thing Rs have on health. Inevitable & some D political advantages per ACA even tho bad policy

My first thought in response was, "since Republicans always toss in "means-testing" when they talk up entitlement "reform," why not "means-test" the eligibility age? As Paul Krugman has pointed out repeatedly, "Gains in life expectancy have been very strongly correlated with income and class; those with lower incomes and lower status...have seen very small gains in life expectancy." So perhaps eligibility could be tied to income or assets. That might create some marginally perverse incentives, but that only underscores what a dumb idea raising the eligibility age is in any case (it will raise total healthcare spending, as Sarah Kliff has demonstrated).

As I learned through a subsequent Taylor tweet and 11/28 post (see below), Austin Frakt has a more symmetric proposal:

If raising Mcare age is to align it with SS, where are the provisions that are the analog of (effectively) buying into SS at 62?

This apparently stimulated Taylor to envision a more dizzying trade-off, in which Democrats not only buy Republican buy-in to the ACA exchanges in exchange for raising the retirement age, but trade the beginnings of premium support in Medicare for a first step down the age ladder toward " Medicare for all." Here's his multi-step:

• Any state that sets up an ACA exchange, in that state, we will demonstrate competitive bidding in Medicare advantage 2 or 3 years later, using the experience of the state exchanges to inform (Austin’s FAQ on comp bidding is great).
• Two or three years after that, we move to allow a “Medicare buy in” for persons younger than 65, say to 62 (or 60 or whatever). This will be ~ 5 years after state based exchanges have been up and going and will give time to see if there are parts of states in which private plans don’t seem to be working out (most likely rural areas with few people, and more difficult to set up networks, etc.). There are endless permutations (only private options in early Medicare years, different benefits, depends on how many plans available in a county, etc.)
• If we were going crazy with this, then after that, allow states to start buying in low income portions of Medicaid (not duals and long term disabled) into private insurance sold in exchanges, after they were up and going and the risk pool is getting larger and larger.
• Then we might start letting more and more people the choice of buying in the exchange and over time, slowly move away from health insurance as a benefit of employment.

Taylor has also devoted a book -- summarized in this post -- that envisions a different kind of long-term liberal/conservative fusion: catastrophic coverage as Medicare-for-all, with private supplemental insurance offered through state exchanges. 

Taylor is not scared of premium support in Medicare -- though he wants to use the exchanges in the ACA as a test-of-concept, an idea that has the added benefit of giving Republicans an incentive to try to make the ACA exchanges work.  

My question is whether managed competition in Medicare wouldn't weaken the government's already too-weak pricing power. I would prefer to see things move in the opposite direction, with a strong public option in the ACA eventually crowding out the private plans, or perhaps rendering them designer options or simply alternatives that work better for a subset, like Medicare Advantage plans today (perhaps trading off choice among providers for more comprehensive benefits). What I'd like to know is whether there's a way to maintain "choice," i.e. private insurance options, while granting the government control over pricing for healthcare services, as virtually every other wealthy country does.

As for the current debate about curbing future spending, I would prefer to see Obama go on offense, proposing Medicare cost controls that are likely both to be effective and to offend Republicans (or provoke their fake outrage).  But perhaps that's unrealistic.

P.S. I want my own damn Medicare @ age 65, and I reckon most other Americans do too.