And they would stay in business why, with NO profit allowed? Why not? And if they packed it in, there'd be no pr0blem in replaciing them. The private health insurance that operates in the UK in parallel with the NHS (BUPA etc) is non-profit, and seems to do very nicely for itself.

So long as a business covers its operating costs, including the wage and salary bill, and costs of borrowing money if need be, then it can stay in business. Racking up those costs by trying to cream off a profit just serves to damage its viability.