When House Republicans euthanized their unloved and unlovable American Health Care Act moments before a scheduled floor vote on Friday, they handed the Democratic Party its first real victory in ages. ObamaCare's defenders should savor the moment and gleefully Instagram a thousand pictures of this delicious revenge platter. But embedded in Friday's well-deserved GOP humiliation is an important lesson for future Democrats, too: Don't let your politics get too far ahead of policy reality. One will eventually catch up with the other.

Speaker Paul Ryan's microphone was still cooling Friday afternoon when leading progressive voices urged Democrats to start fighting for single-payer health care, a reminder that Democrats are hardly more united about health policy than Republicans. While 2016 nominee Hillary Clinton ran on a platform of tweaking rather than abandoning the Affordable Care Act, Bernie Sanders premised his primary campaign in large part on a radical promise to ditch Obama's signature legislative achievement in favor of extending Medicare to all Americans. His pitch proved appealing to a party base that settled for the certainty of the ACA in 2010 but still pines sorrowfully for the public insurance option that died in Joe Lieberman's cynical hands.

The phenomenal success of Sanders' insurgent socialist campaign proved again that the ACA was unpopular in large part because millions of Americans think the state should be doing more rather than less. So where does this leave Democrats on the issue today, in the wake of the GOP's colossal failure? While the Democratic Party's membership and leadership in Congress remains committed to incrementally improving the ACA, that could change over time, particularly if an emboldened progressive wing targets moderate Democrats in 2018 and 2020 primaries. And the appeal of "Medicare for all" would only increase if President Trump and his allies succeed in their avowed plan to malignly neglect ObamaCare in the hopes of pinning its failures on Democrats.

Yet there are a number of important questions about any single-payer plan that remain not just unanswered, but mostly unasked. Democrats need to learn the right lessons here. After all, it was by forsaking difficult questions in favor of grandstanding that the Republicans got themselves into this health-care mess to begin with.

Let's imagine that, somehow, progressives succeed in enacting "Medicare for all." (This requires a series of events including but not limited to winning back the House, Senate, and White House, and then getting pretty much every Democrat in D.C. on board with a radical plan to totally remake American health care.) But let's imagine that it happens. What does the transition period look like between the passage of such legislation and its full implementation? What would happen to the health insurance companies that employ over half a million people? Would they be compensated for their losses? What would happen to the medical debt of doctors who would almost certainly face diminished economic prospects under single-payer? (Most Americans think physicians are rich — true in some cases — yet many doctors rack up over $200,000 in debt to attend medical school.)

Health-care is a giant sector of the economy, but also a delicate ecosystem. And the areas of greatest need in our system — for instance, primary care doctors and rural areas — generally pay the worst and already have trouble attracting physicians for that very reason. What happens to the supply and demand of care when tens of thousands of doctors earn less?

Do we have even remotely the civilian bureaucratic know-how we would need to scale Medicare up to the entire 320-million-strong population of the United States? The Centers For Medicare and Medicaid Services employ more than 6,000 people. That number would probably need to be, conservatively, quadrupled. Remember that a committed and well-intentioned Democratic administration had trouble just setting up a website for a tiny fraction of the number of people who would be covered by a new single-payer system. Running a nationalized health-care system would be considerably more complicated than cutting monthly Social Security checks to people.

Political questions abound as well. Republicans spent seven years hammering ObamaCare, which remained mired in negative approval ratings. Yet as soon as the GOP captured total control of Congress and the presidency, the politics of the issue changed quicker than a Great Lakes weather forecast. Suddenly, Americans who just months ago were complaining about the ACA's deductibles and coverage options were faced with the prospect of losing their insurance coverage altogether, along with their right to be covered if they have a pre-existing condition. Since November, ObamaCare has drifted into majority approval, and the Republicans' hot, hastily conceived, cruel, vindictive mess of an alternative was opposed by a whopping 3-1 majority.

A similar problem would vex Democrats almost immediately, in the same way that it did when they got to work on the ACA in the first place. It's what happens when various stakeholders in existing, complex, and flawed processes realize that their interests are deeply threatened. The maximal version of "Medicare for all" would involve, in a quite literal sense, stripping hundreds of millions of people of their existing private insurance coverage — and thus also their expectations about the timing, expense, and reliability of their medical care. While navigating the insurance bureaucracy is frustrating even in the best of times, at the end of the day a significant percentage of the public is likely to react vehemently to any attempt at wholesale, radical change. Democrats might be better off fighting for the public insurance option that so narrowly eluded them in 2010.

The Democratic caucus has moved to the left since 2009 — largely by attrition. But has it moved far enough to the left to pass single-payer health care? I wouldn't bet on it. Many Democratic members of Congress have spent the better part of their professional careers fighting to pass the Affordable Care Act, and then fighting a rearguard action to defend it against relentless Republican subterfuge. From purposefully undermining it at the state level to challenging it in court to voting dozens of times to repeal it while Obama was president, the GOP has waged a scorched-earth campaign against the ACA and has failed spectacularly. For Democrats, launching another huge, divisive struggle over health care would be like if Truman had decided to go ahead and fight the Soviets over Eastern Europe at the conclusion of WWII.

None of this is to say that the Democrats should absolutely not pursue a version of single-payer. But if they do, they must do the kind of legislative preparation, messaging outreach, and hard thinking that eluded what passes for policy wonks in today's GOP. They might just find that improving the ACA rather than replacing it with an entirely new system would be not just the best policy option, but also the only one that is possible.