I'd say we already have two systems. The private insurance providers, and Medicare. The results will be similar if we make it universal. Namely, the government system will not pay the total cost of health care, and therefore, hospitals are raising their rates on private insurance users, to cover (read subsidize) the government program.
In other words, you right now, if you have health insurance, are subsidizing the government medicare system. As in, you are paying a tax, on top of your medicare payroll tax, to subsidize the system. Aren't you glad?
Further, there will never be an official two-tier system for health care. The reason is because the whole complaint with health care is... it's unequal. Installing a two-tier system defeats the purpose.
I say officially because in reality there's always a two-tier system. The Canadians that can afford to come to the US, and pay for their own health care, do so. The ones that can't are left to die in waiting rooms. This is why people in the UK fly to India 'pay-for-service' hospitals while their poorer countrymen die in waiting rooms. So there's always a two-tier system in one way or another.
