I'm actually in favor of something along the lines of this.

Each state has their own medicare fund, which is funded by each individual state and covers each state's own cost. Having a massive federal based insurance structure is going to be bureaucratic and difficult to manage. Allowing local governments to manage is easier to handle, as long as follow a set of guidelines agreed at a federal level. Federal government works with each state's medicare providers and health providers to bring costs of services to more reasonable prices. Everyone is covered and the private insurance industries no longer inflate the costs of medical services.

Here's the problem: you've know probably put a ton of people out of work. You have massive unemployment and now your revenue pools are smaller to work from. The aging population is growing and not contributing to the funds. What do you do?

Single payer isn't some fairy wand problem solver that everyone believes it is. It's a massive, expensive and disruptive change that has a high chance of failure, on a nationwide scale.