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).