For six years, Republicans in Congress have promised that very, very soon they’d release their plan to “repeal and replace” the Affordable Care Act. Just you wait, they said back in 2010, when we put out our plan America will see how terrific our health-care ideas are. They also said that in 2011 — the plan was coming, hold on! They said that in 2012 — any day now, here it comes! They said that in 2013, and 2014 and 2015 — just give us a few more weeks, and you’ll have it! Well, now it’s 2016, and House Speaker Paul Ryan (R-Wis.) today released something that sort of looks like a “plan” if you just focus on the middle distance and take it in through your peripheral vision.

If you want to read Ryan’s plan, here’s an executive summary, and here’s the somewhat longer version. It’s light on details — such as how much it would cost and how many people would lose their coverage because of it — which isn’t all that surprising, given that the more specific you get, the more problematic things become. But it still illustrates the dilemmas Republicans face on this issue and their inability to solve them.

We’ll get to the potentially catastrophic effects of this plan (and I don’t say that lightly) in a moment. But first, let’s briefly look at what it contains. The starting point is the assertion that the ACA is a complete and utter disaster from top to bottom and therefore can’t be changed, altered or reformed, so it must be completely repealed: “This law cannot be fixed. Its knot of regulations, taxes, and mandates cannot be untangled. We need a clean start in order to pursue the patient-centered reforms the American people deserve.” But after saying this, Ryan proposes to put back all the things about the ACA he thinks are popular. No denials for preexisting conditions? Don’t worry, we won’t take that away! Young people up to age 26 being allowed to stay on their parents’ insurance? We’ll give you that, too! The ban on “recission,” where your insurer cancels your plan if you get sick? It’s in there!

So here’s what else is in the plan: Ryan would eliminate the individual and employer mandates; shut down the insurance exchanges; cancel the ACA’s expansion of Medicaid and then cut the program and convert it to block grants so that states could kick people off; move Medicare to a “premium support” model, which essentially means privatizing it and cutting it back; eliminate the ACA’s subsidies for low- and middle-income people, which would be replaced by a refundable tax-credit; promote health savings accounts and “mini-med” plans that cover virtually nothing; cap the tax exclusion for employer plans, which he presents as a friendlier alternative to the ACA’s “Cadillac tax” but which in effect is pretty much the same thing; and limit the amount victims of medical malpractice can sue for, along with a few other things.

One important note: Despite what Ryan says, the plan doesn’t actually maintain the prohibition on denials of coverage for preexisting conditions, which may be the single most popular element of the ACA. It does so only if you maintain continuous coverage, beginning with a special one-time open enrollment. If you don’t, you’ll find that insurers can once again deny you because of your medical history, just like in the bad old days. And his answer for people with costly medical conditions is high-risk pools, which are just about the worst way possible to provide insurance (they segregate the costliest patients together, making coverage impossibly expensive).

So what would happen to this plan if Donald Trump actually became president and Republicans retained control of Congress? Trump himself couldn’t care less about the details of health-care policy — he’d probably sign whatever Congress put in front of him (don’t forget that his central health-care promise was to repeal the ACA and replace it with “something terrific”). But would they actually fill out the details and pass Ryan’s plan? There are strong reasons to think the answer is no.

That’s because this plan, like almost any repeal-and-replace idea Republicans have, would cause absolutely cataclysmic upheaval in Americans’ health care. I cannot stress this strongly enough. Even if you accept the Republicans’ argument that it would eventually bring us to health-care nirvana (which I obviously don’t), in the short and medium term it would be a nightmare. It would be much more disruptive than the implementation of the ACA was in the first place. One of the ironies of Republican rhetoric on this topic is that on one hand they complain that the ACA is so complex and made so many changes, touching every part of the American health-care system, yet on the other hand, they claim they can undo it all with the stroke of a pen, and it’ll be no problem.

But they’re right on the first part. If you repeal the ACA, that means not only what we’ve already talked about, but also things like reopening the “doughnut hole” in Medicare prescription drug coverage, and moving Medicare back to the fee-for-service model the ACA has successfully begun a move away from, and taking away subsidies from small businesses, and taking away funding for community health centers, and bringing back cost-sharing (i.e. you paying money) for preventive care, and shutting down all the pilot programs the law created to test out new ways of delivering and paying for care, and a hundred other things that are going to cause enormous problems for hospitals, doctors and patients.

But that’s just the stuff that won’t get all that much attention. What will? The fact that when you repeal the ACA, you’ll be tossing tens of millions of Americans off their health coverage. The nonpartisan Congressional Budget Office estimates that in the first year after repeal, there would be 20 million more people without insurance.

Just imagine that: 20 million Americans losing their coverage all at once. Consider the parade of horror stories in the news about people being destroyed financially, and more than a few dying, because they can’t afford health care. Think that would pose a bit of a political problem for Republicans?

Which is why Ryan’s “reform” is not going to happen. It would be political suicide, and Republicans know it. If they do get the chance, they’ll pass something much, much more modest. They’ll call it “repeal and replace,” but it won’t be anything of the sort.

As Paul Ryan opts out of reelection bid, we revisit his career in photos

In this photo taken Feb. 2, 2016, House Speaker Paul Ryan of Wis. speaks in Washington. Ryan said Wednesday, Feb. 3, 2016, Republicans need to stop fighting angrily among themselves and not be distracted by guns or other "hot-button" issues that President Barack Obama raises. (AP Photo/J. Scott Applewhite)