The problem that I see with our rapidly growing Government is that people have ways of avoiding taxes. For example wives of high earners might work at home providing goods and services for in family consumption rather than in taxed worked, people might deal more in cash, or provide more of their own services, use barter etc.
For example a family with a low earner and high earner might keep the low earner working to help pay for the insurance, but if Gov. provides the insurance the low earner might quit a taxed job to provide services at home.
So the question is how much tax will Americans pay before tax avoidance starts to reduces the Government income.