This may not be the case, since much research is subsidized by the government and educational funding providing labs that train the scientists the pharmaceutical companies utilize. Single-payer may result in lower costs and therefore more money for support of research and laboratories. Also, pharmaceutical companies would not need to spend vast amounts for marketing their drugs direct to consumers.
In theory we could nationalize the whole industry, and let government bureaucrats decide which clinical trials to fund. I'm skeptical whether that would produce better results. Government employees with no skin in the game have a poor record of picking winners.
I doubt it would. Private drug companies would still exist and charge the same money regardless of whether the insurance is paying for it or "the single payer system".
We are the leader in it partly because we pay these exhortation prices when the rest of the developed world simply won't play that kind of game.
I'm okay with biting that bullet, and taking a global reduction of health research by some double digit percent for awhile, but that's a serious unintended consequence of single payer.
I'm a Bernie voter who supports single payer, but it's not sunshine and roses everywhere, and crooked capitalism really does do some "not bad" things for us.