A polar ice sheet lodged itself atop the entrance to Hell this afternoon, as the House of Representatives passed, by an overwhelming bipartisan margin of 392-37, a fix to the Medicare formula for reimbursing doctors, putting Congress on the brink of ending a saga that has been marked by punts and short term fixes for well over a decade. According to Sahil Kapur’s report from the House floor, the celebratory outbreak rivaled the victory parades that marked the end of World War II:

Everyone from Speaker John Boehner to Minority Leader Nancy Pelosi to their deputies and committee leaders and underlings sang the praises of a massive Medicare overhaul bill, giving the equivalent of Oscar acceptance speeches by effusively thanking their staff and colleagues for making it happen….
“Don’t look now,” said Rep. Renee Ellmers (R-NC), “but we are actually governing.”

Don’t expect it to last. While there’s been a lot of chatter about how the bipartisan deal on the Medicare “doc fix” could herald a new era in which John Boehner stiff-arms the right to make legislative compromises with Democrats, there are reasons to assume that there could still be plenty of chaos ahead.

To be sure, the Medicare doc fix deal is an achievement. The liberal Center on Budget and Policy Priorites and the Center for American Progress both endorsed the deal: It brings stability and certainty, the means for paying for it is acceptable (it’s mostly by raising premiums on very affluent beneficiaries), and it extends the Children’s Health Insurance Program and funding for community health centers.

Senate Democrats continue to block the compromise out of concerns over abortion language. But as Danny Vinik writes, it is a genuine compromise, and it’s probably only a matter of time until Senate Dems cave. After all, it has been endorsed by Nancy Pelosi and has now passed the House by overwhelming margins.

But that doesn’t necessarily mean this portends lots more compromise ahead.

There are plenty of differences between this situation and the other potential chaos points that loom in coming weeks and months. For one thing, as Dem Rep. Sander Levin said on the House floor today, the basic outlines of today’s compromise have been in place for a year. For another, as Paul Kane and Jason Millman write, “a significant bloc of conservatives supported the legislation,” leading to a split among the most “rebellious” of them. So the price on the right might not be too high.

Also consider the specifics of the battles that lie ahead. The Highway Trust Fund is set to run low on money this spring, which could stall infrastructure projects around the country and cost jobs, and Republicans say they want to replenish the fund. But that will require agreeing on an actual way to pay for it, which will be harder in this case than it was for the Medicare doc fix. A short term punt is very possible here.

Beyond that, another big challenge for Congress could come if the Supreme Court guts subsidies for millions in three dozen states. While House and Senate Republicans have made nice noises about offering contingency plans, their offerings have been short on specifics. It’s very hard to imagine a Republican consensus developing behind federal spending to keep those subsidies flowing, when conservatives will be agitating loudly for Republicans to get out of the way in hopes the exchanges collapse.

What about the budget and tax reform?  According to the CBPP, the Republican budgets get two thirds of their spending cuts from programs that help lower income Americans, and include zero in new revenues. There aren’t any signs Republicans intend to suddenly embrace new taxes on the wealthy, which would probably have to be part of any tax reform deal (even some reformist conservatives are urging them to accept this notion). Republicans are gearing up for a reconciliation vote to repeal Obamacare. That will be vetoed, but some Republicans are still talking about using spending battles later this year to continue targeting the health law and Obama’s environmental regulations. Not a lot of grounds for Kumbaya in this area, either.

Then there’s the debt ceiling. Republicans will almost certainly end up caving and agreeing to a clean debt limit hike. But as we’ve repeatedly seen already, even when GOP leaders themselves publicly admit they will not allow default, they still drag us through a long bout of brinksmanship en route to that point, to prove to conservatives that they were willing to fight the good fight until the bitter end — and that brinksmanship itself risks doing damage.

So enjoy today’s victory parade while it lasts!