Eh. In practice, what you really need to know here is that this disease isn't realistically ever going to be an epidemic in the modern developed world, *even* if it develops a strain that is 100% resistant to all antibiotics (which thus far hasn't quite happened). The conditions for massive spreading just aren't there. It was a large problem in the medieval world, but conditions were very different then. The plague doesn't normally spread from person-to-person directly, in the manner of something like an influenza or a coronavirus. I'm not saying that can't ever happen at all, but it's far too unusual to ever result in any kind of epidemic. To have a bubonic plague epidemic, you have to have a completely out-of-control population of intermediate carriers (principally, rodents) living in close proximity to the human population, and a lot of biting insects (principally, fleas) that routinely prey on both. We're talking full-on Monty-Python-and-the-Holy-Grail levels of societal poverty here, people laying down in straw beds because that's what's available, dealing with flea bites by scratching, grain stored in burlap sacks, rats everywhere, mice everywhere, the whole nine yards. If you clean up your society and control the vermin, ipso facto, the plague is mostly contained and hardly spreads at all.
Sure, it's not completely extinct. But it doesn't need to be, because it doesn't spread that readily. You're five thousand times more likely to be killed by a drunk driver, than to be infected by the plague bacterium. (This is assuming you live in America; yes, I looked up the actual numbers.) And most people who do get infected, don't die, because it's treatable these days, because, you know, modern medicine and stuff.
Cholera, similarly, is not an epidemic threat if you have anything resembling modern sewage treatment. So you can cross that one off your panic-immediately-if-there-is-one-case list as well.
The one that would be all kinds of scary if it ever got loose in the human population again, is smallpox. That thing spreads almost as readily as influenza, and most countries haven't vaccinated for it in decades. In America, routine vaccination was stopped more than fifty years ago, so most of the population, has not been vaccinated. We do *have* quite effective vaccines for it, but in the event of an epidemic, I doubt whether we could ramp up production fast enough, to keep up with the terrifying rate at which smallpox spreads. The one notable piece of good news is, it doesn't mutate much, so once any given patient is vaccinated against smallpox, they won't need the vaccine again. Booster shots not required, thank God. If that weren't the case, we'd probably still be losing a double-digit percentage of the human population to it every generation or so.