Nothing wrong with the quality of health care in Canada...I hope you aren't suggesting the US is getting more, or even the same bang for their buck.
The average uninsured person is certainly getting less and the average poorly insured which is most of the barely insured is getting little to no value compared to most socialized systems. The well insured those with full covered dental, eye, physical, mental, and long term improvement can receive much better and faster care across the board than most socialized systems. These are the people that have to be sold on socializing health care. It is a hard sell, no wait in a room full of medicare and well fare recipients is a great experience. Sitting in a room full of sick people for hours is a really good way to get sick and it is depressing. Private diagnostic rooms with experienced doctors who have the time to listen and diagnose accurately. The well insured who are smart enough to use their insurance wisely do not want to go back to what it was before they earned their coverage. They already pay a price above and beyond the rest for better coverage and that price includes paying part of the treatment for those with less insurance.
That's the problem...turn it over to the market and the price becomes what the market will bear, and everybody has to get their cut. That's why it is going to be impossible to turn it around, there is too much money to be made. You're right about the potential doctor shortage as well...for the same reason. There's too much money to be made.