On the one hand, why leave your signature legislative achievement in limbo?
But the fact is that if the mandate falls next week, nothing will happen. Then the next week, nothing will happen. Nothing again the week after that, and nothing will continue to happen for the next 70 weeks, which is roughly when the bulk of the law takes effect. In the meantime, Congress can do something, or it can do nothing, Democratically controlled states can step in, or not. If lawmakers move aggressively and fix it in advance, great. If they don't and then in 2014 the reforms start to wobble, Congress will do something, or a lot of states will pass their own laws to broaden the risk pools, and things will settle down. That's my hunch at least -- that if the policy becomes unsustainable, then the politics of not fixing it will be unsustainable too.
Presumably that's why President Obama's telling his supporters he might have to "revisit" health care in his second term, rather than, say, in the middle of the campaign, when he'll probably want to avoid using the word "mandate" altogether. If he loses, then of course the mandate's probably dead. But in that case, it stands to reason that the mandate and much of the rest of the law will vanish anyway, regardless of what the Court does. Which I guess is a long way of saying there's an appeal to both approaches but it's the sort of problem that, perhaps inelegantly, will eventually solve itself.