When one has an intestinal infection, very common where I live in Mexico, and nothing else works, some cillan will work. Meanwhile, back at the ranch, what you say holds for nasty hospital infections, but most of the same old antibiotics work for intestinal and most infections here in Mexico for many years, like chloromycetin for intestinal infections. And this is something the medical professions can work on, versus the latest pharmaceutical innovation on how to keep someone who is dying of xyz alive for 10 more minutes.

I'm not an expert, but plain penicillin may be quite useful in the future. There is generally some cost in robustness for an organism to adapt to anything, which is why most germs were NOT penicillin-resistant prior to WWII even though penicillin had evolved maybe a hundred million or more years ago (wild guess). Because the organisms using it were rare. By the same token, once most humans don't have it, regular strains of germs may get the upper hand over the so-called "supergerms" for the same reason they were more robust in the past. Stuff like MRSA is only "super" in the context of pervasive human antibiotic use, it's probably of lower efficiency than it was before to "buy" this adaptation.

The decentralization of medicine may not bode that well for "supergerms" and if few people have antibiotics, regular penicillin may well become quite useful again. It's a constant evolutionary tit-for-tat and microorganisms show it very directly due to their fast reproductive rate....

Indeed, it was recently found that some old "basic" antibiotics are useful against MRSA now... since they haven't been used much.

In nature, antibiotics are useful DUE TO BEING RARE, whether in bread mold, frog slime, etc. It is not energetically worth a germ's evolving to exploit the niche since it would pay a bigger cost in some other way. We know this is true because bread mold, frog skin, and all the other natural antibiotics still work after millions of years. They probably are periodically overwhelmed by bacteria if the owner gets too populous, and conserved within the organism's genome for later.

It's all about evolution.

ymmv

Pinealone, the good news about antibiotic resistance is that it is usually temporary, not permenant. If al penicillin derivatives were withdrawn from a medical community for 1 year, the suscetibility to penicillin would skyrocket. Many bacteria would eject the plasmid containing the penicillinase gene as it would no longer convey a competitive advantage, and simply consume energy (on a cellular level) transcribing into proteins. Thus, resistance is lost (until the use of penicillin resumes as a therapeutic intervention).