What is it that makes an implant irreversible? Could future regenerative treatments work to reverse it?

[Gt1956]

There would be no way to reverse an implant.
All the tissue that causes an erection is removed and replaced by the cylinders.

If penile transplants become available, you think implantees couldn't get one?

Live in the now. Don't daydream about science fiction outcomes. What gives you any idea that the donor supply of penises will be in much better condition than yours is?
A penis isn't required to live a life. In my opinion it is very unlikely that penis transplants will ever be common. I suggest that you concentrate on getting comfortable with proven existing treatments.

[Howling8]

That would be interesting if ever perfected. My surgeon, Dr Guise, apparently left a lot of my tissue as I can get a boner that's about 2/3 of my pre-op if really aroused and it's good enough for a blowjob or fucking. When fully pumped at 40 pumps it looks just like my pre-op if not bigger (according to my wife)