First, let me say I'm no fan of ObamaCare. I think it is structurally ruining our healthcare system; driving up costs; and putting lower income people into insurance policies with extremely high deductibles and high out-of-pocket expenses.
That aside, at least 12 million Americans have gotten their health insurance through the exchanges. Of which, nearly 85% are getting subsidies; with the average subsidy being 73% of their cost of insurance. By extension, these people have entered in a "good faith contract" with our Federal government.
While I am not a lawyer, I have taken enough business law courses to understand that a "good faith contract" could be a problem for Donald Trump and the Republicans who would necessarily repeal ObamaCare. I think, theoretically, the collective of those receiving subsidies, and through no fault of their own, lose those subsidies, could sue in federal court (or even the Supreme Court) to maintain them on the basis of "good faith".
Additionally, I think the repeal of ObamaCare will result in a public relations nightmare for Trump and the Republicans. You know very well that the liberal media will work overtime to find someone who is harmed or has even died as a result of completely losing their insurance because of the lack of a subsidy. Once again, the Republicans will be broadly painted as being heartless.
I think a better tactic would be to grandfather, in place, all those now receiving subsidies. Drop the individual and employer mandates, and retain the requirements that insurance companies can't deny a person insurance on the basis of a pre-existing condition.
If the Republicans do their jobs and create a new healthcare law that is better than ObamaCare, those still in ObamaCare should naturally move to the new system. Just my opinion.
ObamaCare Subsidy Calculator and Statistics: https://www.healthinsurance.org/obamacare/subsidy-calculator/
Good Faith (Law) - Wikipedia: https://www.healthinsurance.org/obamacare/subsidy-calculator/