An important caveat is that as long as there are 41 Democratic senators to mount a filibuster, total repeal won't be easy. But if Republicans control the White House and both chambers of Congress (a real possibility come 2013), they could unravel the law by deliberately botching its implementation and potentially muscling through repeal of its less popular provisions -- like the individual mandate -- before the more popular ones take effect.
A GOP president could significantly weaken the Affordable Care Act using executive power alone: legal and health experts agree that the administration has considerable flexibility to grant waivers from its regulations and mandates. Pair that with a Congress and dozens of state governments hostile to the law and it's in real danger.
If Republicans don't capture the presidency in 2012, they may still be able to limit some funding for the health law's implementation, but repeal would essentially be out of the question -- and the road would become far bumpier in 2016.
One reason is that public opinion of the Affordable Care Act may well improve once the major benefits kick in, as was the case with Medicare and Social Security, both of which were highly controversial at time of passage and likewise slammed by Republican opponents as ruinous to freedom.
Most of the Affordable Care Act's benefits take effect in 2014 -- including guaranteed coverage regardless of pre-existing conditions, a ban on annual caps for coverage, the creation of insurance exchanges to lower costs for consumers and small businesses, and the Medicaid expansion and subsidies to help low-income people buy insurance.
President Obama, if reelected, will be highly motivated to ensure that these benefits are widely enjoyed. A Republican president, however, could slow-walk and downplay them, if not push Congress to snatch them away, before they're felt.
Another reason repealing the law becomes harder by 2016 is that key provisions will be baked into the cake of American health care, and returning the system to an earlier time period could be politically tedious and expensive.
For example, letting insurance companies return to denying coverage to sick people after the fact would likely create an uproar. Breaking up the exchanges once they take effect would mean rolling back consumer bargaining power to get cheaper prices for plans. Stripping coverage away from newly insured individuals would drive up long-term deficits and increase the free-rider burden on taxpayers.
There's no predicting how the political landscape will look in four years. But the danger for Republicans is that as time passes, their narrative of the law as an agent of government tyranny could unravel once most people realize that, apart from some new regulations and subsidies aimed at expanding coverage in an already heavily regulated and subsidized health care system, the Affordable Care Act isn't there to harm them.
If the Supreme Court strikes down the individual mandate, keeping the law alive will be a slog for Democrats regardless. But if not, Bachmann's urgent warnings to her anti-Obamacare allies are well-grounded: time is not on their side.