Randy Barnett wrote his thoughts about severability in Texas v. U.S. over at Reason.com and here is my comment.
The individual mandate is an example of why I believe the Affordable Care Act was a bunch of dumb ideas that were poorly implemented. The individual insurance market as envisioned by the ACA depended on a carrot and stick approach. The carrot was affordable health insurance for the unsubsidized healthy people to lure them into the market willingly. This is how insurance companies make the money to pay for their unprofitable customers. The stick was the individual mandate. The individual mandate was designed to be scary, not effective. It would never have an influence on healthy customers like affordable health insurance. In 2010 individual insurance rates were already too expensive so healthy people made their adjustments. Some stuck with their grandfathered plans. Some went to alternative insurance products. Others dropped their insurance because they were exempt from the mandate because health insurance premiums would exceed 8.15% of their adjusted gross income. Insurance companies lost their best customers but were largely protected by the Risk Adjustment, Reinsurance, and Risk Corridor provisions. There is no free lunch. Like all dumb ideas that are poorly implemented, the American government got stuck with the bill.
The only portion of the ACA that must continue to exist for the subsidized individual health insurance market to continue to exist is the Risk Adjustment, Reinsurance, and Risk Corridor provisions. If we want to continue to subsidize health insurance premiums for those people earning less than four times the federal poverty level then it will be born the general population rather than the unsubsidized healthy customers. For the unsubsidized healthy customers, this is sweet revenge. The individual mandate has always been a moot point.
Back in 2016, I wrote a post, The Health Exchange Transformation Is Almost Complete, in which I made the argument that the individual health exchange had a better chance of reverting back to a high-risk pool exchange than a market-based exchange. It all depended on the affordability of health insurance for unsubsidized healthy customers. If you do not keep your best customers, the government will be left holding the bag. When it comes to the individual mandate, the people who wrote the ACA were not that smart. The most important thing that matters to a customer who might get penalized is not the penalty but affordable unsubsidized health insurance. Affordable health care has always been the primary objective of the Affordable Care Act and the American people. Our politicians seem to have forgotten that aspect of the ACA. If the individual mandate has always been a moot point then severability has always been a moot point, too.