The success rate of most transplantation is between 80-90%, however it also depends on the type of operation just like you've mentioned. Let's use the transplant of human heart as an example, in the early 1970s, the success rate is below 20%. But in the 80s, after the introduction of cyclosporine, an immunosuppressant, then we started achieving up to 85-90% success rate and despite that, the long term survival is still uncertain. In other transplants like the kidney and the lungs, there's been a notable high success rate.

Another factor is that people don’t finish courses of antibiotics

At times with normal drugs, I do fall into the category of "not completing my dose" as soon as I'm starting to feel better but I don't do such with antibiotics since I already know the implications.

I am afraid antibiotics may soon become useless as such

For antibiotics to become obsolete and useless, well, maybe yes and maybe no. For now, though, they are still useful.

Thanks for coming by, @lemouth. I do appreciate your comments.