Most Americans appear to agree with Jimmy Kimmel's belief that no one in this country should have to go without lifesaving health care simply because they can't afford it, or couldn't find a health insurance company willing to cover them. It's a big reason why multiple efforts by both the U.S. House and Senate to repeal the Affordable Care Act, or Obamacare, failed this year. Yet, with an executive order issued Thursday, President Donald Trump attempts to achieve what Congress could not – an effective rollback of the health care law's protections for people with pre-existing or chronic health conditions.

The executive order sets the stage for new health plans that do not have to comply with Obamacare's insurance rules, including requirements that plans cover a basic set of minimum benefits like maternity care, prescription drugs and mental health treatment, and refrain from setting premiums based on a person's age, gender or health status. This could be good news for healthy, young people who buy insurance on their own today. Most likely, they'll be able to find a plan with a lower premium.

The bad news? If you're older or need to use health care services because of a current or past condition, you'll likely be charged a lot more for your coverage. Many low-income people could be protected from these rate hikes, because the Trump administration can't repeal the law's income-related premium subsidies. However, if you're not eligible for those subsidies – and an estimated 7.5 million people buy insurance on their own without federal financial help – you could face increasingly high premiums.

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Individuals with health needs could also find fewer plan options available to them. The plans encouraged by the executive order will be allowed to screen people based on their health status, a practice called underwriting. If you have something in your health history, such as a brush with cancer (even if in remission), asthma, obesity or anything that makes you look like a risky bet, these plans will deny you coverage outright or charge you an outrageous premium. They may also not cover the critical benefits you would need, such as prescription drugs or mental health services.

The administration cannot repeal Obamacare's insurance protections – those are written into law – but many insurers could likely stop offering plans that comply with them. Why would they? Those plans, which are not allowed to underwrite and must offer a comprehensive set of benefits, will be the coverage of last resort for people with pre-existing conditions. Few insurance companies want to sell plans that only appeal to sick people.

What's particularly ugly about the proposed action is that there is strong evidence the Obamacare marketplaces were starting to stabilize after the rocky early years. With a few, relatively minor policy fixes, these markets would continue to provide consumers, healthy and sick, with comprehensive, high-quality, affordable plan options. Yet, since coming into office, the Trump administration has systematically tried to undermine these markets with a series of actions and threats. These have injected a great deal of uncertainty about the future of these markets for participating insurers and have directly caused dramatic, double-digit premium hikes for 2018.