Creating a single national health insurance pool is not likely to destabilize the economy by supplanting the private health insurance industry. This industry insures a relatively small percentage of the population and holds very little of the risk such insurance implies. In effect, insurance companies function as middlemen, bundling risk packages to distribute to other, larger companies and so serve a limited purpose. Were insurers to handle claims for a national pool as they do for the Medicare program, any destabilization to the economy more broadly would be further minimized.
Jacqueline Fox, The Private Insurance Market: Not Very Big and Not Insuring Much, Either, 46 J. L. Med. & Ethics 877 (2018).