employer provided health plans are already moving to making the recipients more "price sensitive" to low level care through higher deductibles and co-pays - but there is a limit to which that works with health care - a sick person wants care, they don't want to shop their MRI or open heart surgery like buying a car. that's just the reality of life.
if the employer provided system collapses - there will be a consensus amongst americans for universal medicare. the Dems will promise to fund it by "taxing the rich", and americans who fear the loss or dilution of their employer provided plan, will be more then willing to hand them their votes.
You have a point that for many medical services, consumers aren't really able to do price maintenance, and it really is insuranc companies that do so. The whole issue is hideously complicated. The upside is that I will be dead, before it all really falls apart.