If everything is covered under funding based on the actual costs, how do the hospitals lose money? It obviously wouldn't be the exact same payments that are happening now because if everyone is covered under one set solution then the coverage would be more comprehensive and there wouldn't be overflow backup through the current bloated private programs, so the payments made to hospitals would of course be restructured.
You also seem to like glossing over how much it saves lives and long-term money because of immediate expenses. Yes, an immediate increase in what the hospital charges will occur when new technology is being purchased due to a response in a widespread change in health care, but that's also going to mean they'll be that much faster about identifying and resolving that issue in the future which means less money spent overall. When you're talking about basic public coverage being built on spending across the country then it can become more profitable to prevent than to treat, if you want to be cynical about it.
If prevention is the focus then you have fewer hospital readmissions, fewer nosocomial infections, improved reporting across the board, and fewer Medicare Advantage plans needed which results in huge savings in medical costs performed by the government (all of which are things that ACA aims to improve even further with Medicare). When hospitals are going to be dealing with more flat-rate prices instead of individual basis income then it's going to be increasingly more cost-effective to deal in even larger sweeping motions that help everyone at once.

