I want to note one thing about the risk to the ACA from a change in the composition of the court: The remaining legal issues about the ACA are statutory, not constitutional, so a Dem congress & president could address them through statutory cleanup, without changing the court.

NFIB v. Sebelius was about the constitutionality of the mandate, which has now been abolished anyway. King v. Burwell was about a drafting error regarding the exchange subsidies; you could fix the drafting error.

The ongoing litigation is about whether the mandate is now unconstitutional because it's no longer a tax bc the penalty associated with it was reduced to $0 -- and if so what other parts of the law should be tossed, too. You could fix that by repealing all mandate language.

I guess you could come up with a *totally novel* theory of why the ACA was unconstitutional, but none of the theories that the GOP has spent the last decade suing under would apply.