Health Insurance is an oligopoly and I would not rule out collective action by some confab of health plans. The GOP vulnerability is rural counties and no one offers plans in them except as a sign of good will.
A “bare” county is a terrible problem. Most are rural. In a bare county, no one can offer any health plan, even if people are willing to pay. If no one has coverage, the local hospital then sees a big drop in revenues and is headed to not making payroll. Aside from the damage to citizens health, the local hospital is the largest employer in most rural communities, so its failure throws the county into economic recession.
The abruptness and timing of Trump’s tantrum gives the admin vulnerability under the administrative procedures act which requires notice for changes in government programs. There is particular vulnerability for the admin cutting off payments to the health plans in the exchanges in Nov and Dec. Do you think their contracts allow for this kind of precipitous action (by a mobster)? Note that the current contracts were prepared and signed by the Obama admin.
This hostage taking is different from the DACA hostage taking. Trump can halt deportation of DACA recipients on a dime. He cannot undisrupt insurance markets once he has disrupted them.
If the way out of our having a mobster in the WH is that he can only incent the GOP to get rid of him by hurting actual Americans, this CSR hostage taking is much less destructive than some other hostage taking that I can think of.