Whether you're a supporter of it or not, one has to admit, long-term, that the Affordable Care Act is, strategically, a brilliant piece of legislation.
I think nobody was really satisfied by the individual mandate (the right sees government overreach, while the left hates private insurance companies who will get fat off of this), but now that it has survived its court challenge, the mandate enables the most important clause of the law: insurers cannot discriminate against customers based on pre-existing medical conditions.
Now, such non-discrimination clauses were tried before in some states, and health care costs skyrocketed because of it, because it makes sense: you're forcing businesses to accept "Big Loser" customers who will always be a drain on resources, so they'll need to fleece the regular customers more to maintain the same levels of profit (or profitability at all, i know little about the operating margins of health insurance companies). The best way to balance that out would be to force everyone to get health insurance, broadening the base (especially since it often tends to be young, relatively healthy people who go without) of people who will pay for health insurance but are less likely to use it, meaning that the insurance companies can be saddled with the Big Losers without having to hike rates across the board.
What this means, then, is that the individual mandate is essential to keeping the important Non-Discrimination feature. So any scheme the Republicans could come up with would have to address Non-Discrimination. Remove the individual mandate but not Non-Discrimination, and rates shoot sky-high, which could lead to an interesting crisis where everyone but the most sick drop health insurance because its too expensive, ruining the entire industry (as then their *only* base would be Big Losers).
Then we get to the fact that Non-Discrimination could easily be made into the new third rail of American politics, especially since insurance companies had Diabetes as a "do not insure" condition in a lot of cases. That's 26 million voters right there, a good chunk of them from red states, and Republicans are really going to say "We're going to make it so that nobody will insure you."? This is leaving aside a lot of other pre-existing conditions, or the biases insurance companies have against women. Huge swathes of voters could be effected, and so we can no longer go backwards in that regard.
Basically, if there is disatisfaction with the Affordable Care Act, the only politically viable routes are the following
A: removal of the individual mandate, with the required secondary task of extending Medicaid to all of the "Big Losers." (to avoid tremendous political fallout)
B: Moving further forward towards a single-payer system.
It's really quite brilliant if you think about it. Either way, more government intervention in health care is the only solution going forward.