I'm not sure I'd be too good at predicting 50 years from now. I'm not sure it's even necessary to go 50 years ahead.
Several countries right now don't have availability of certain antibiotics due to production problems. Australia recently had a problem with piperacillin–tazobactam, which is an important broad-spectrum antibiotic.
Having a drug unavailable because of production is, in many ways, similar to not being able to use it because of drug resistance. What ends up happening is that you reach for other drugs, you result in harm, and you get side effects. If you can't use any antibiotics, which is what will almost certainly happen if we do nothing, the complication rates.... For example, I have an artificial hip. The risk of me getting that infected at the time of surgery was somewhere around 1%. Thankfully I got antibiotics at the time of surgery so the risk went from 5% down to 1%.
If we can't use antibiotics for a simple surgery like that, then one in 20 people who are getting hips, rather than one in 100 people who are getting hips, are going to get infections. For Caesarean sections, it's the same thing. The risks are even higher. It's the same with abdominal surgeries. The list goes on.
For transplantation medicine, for solid organ transplantation, the backbone of that is antimicrobials. It requires a very broad team to be involved, but the backbone involves antimicrobials. Supportive care for cancer chemotherapy absolutely requires antimicrobials. If you have leukemia and you're receiving chemotherapy, you are almost certainly going to require broad-spectrum antimicrobials for weeks.
No cancer chemotherapy, no transplantation, no high-risk surgeries, and that's not 50 years from now; that's 15 to 20 years from now at best.