I disagree. I've heard that argument before, but not seen numbers to back it up.
In fact, for many years Holland had exactly that program (people above a certain income level couldn't participate in the national health care program) and they never had funding issues. They changed their system a few years back, though, to quasi-privatize the national system because of poor care received.
In Holland, you were talking about government provided health care, not health COVERAGE. I think that's different than what's being proposed. (I'm not certain of that, though).
But the posters on this board from Australia and NZ might want to weigh in on the way their governments handle these things, because it's my understanding that it's fairly successful, if a bit beaurocracy-laden (in Australia, at least).
And you didn't address my other issues.