The healthcare industry can't afford to exist if they don't get paid by someone (whether that is the insurers or Medicare/Medicaid). We've seen mass closures of rural hospitals and medical practices as more rural Americans have lost insurance or gotten insurance that has large penalties for using said insurance: https://www.youtube.com/watch?v=18kxPz4Z_g8

Insurers themselves are a mixed bag, many have gone broke as IIRC the gov't managed pool of money they were supposed to pull out of/put money into to ensure no insurer went under from too many unhealthy, newly insured people has been starved of funding under our current administration.

One option is the government can subsidize tests, so that $10,000 becomes $5,000. It's in their best interests to do so.

I also doubt 300M will need testing - by that stage, if everyone is infected, what's the point of testing? It'll probably only be done for the first million at best.

I suppose hospitals are going to want to claim as many tests as possible for the $$$ but at some point the insurers would realize this is ridiculous and stop approving them.