This really is wildly implausible though - it ignores various changes that would be necessary that the American public isn't at all enthusiastic about, such as more significantly rationing (the most expensive) care and significantly cutting salaries for medical professionals. There simply isn't enough of the proverbial "waste" that's easy to wave one's hands at to amount to this quantity of cost savings. American healthcare isn't expensive because of a single source of increased costs, but because of a combination of for-profit hospitals, insurance overhead, incompetent government administration, extraordinarily high medical salaries, too much emphasis on "miracle treatments" that cost a fortune to marginal returns, staggering medication costs (this would be significantly helped by single payer), an unusually fat and unhealthy populace, and moral hazard by medical users that don't see costs. There are more as well, but I got sick of listing them.
Single-payer can help a couple of these, especially with good administration, but a number of them are things the American public has absolutely no stomach for.
Note that I'm not arguing against single-payer, I'm just very skeptical of claims that cost-savings on healthcare are feasible in the next decade or two.