I agree with you.  I don't see a way that a single-payer system at the State level could work.  It would either bankrupt the State or drive providers away to the point of being unsustainable.
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For the U.S. a system like the Netherlands would be the best to emulate.  It's about the same cost as single-payer but it would take a lot less to take what we have now and adopt what the Dutch do instead of trying to create single-payer.  In addition to being a lot cheaper at 10.9% of GDP compared to 17.2% (U.S.), they also have only 0.2% uninsured and a $460/person (over 18)/year deductible.  
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Their system is that all residents and nonresidents that pay income tax are mandated to purchase statutory health insurance from private insurers.  84% of the population also purchase  some mixture of voluntary insurance that covers things like dental over age 18, alternative medicine, eyeglasses and contraceptives.  Premiums for the voluntary insurance is not regulated whereas statutory is.