Future PE will have 3 new possibilities. Two of which have already been mentioned.
Nanotechnology, in which molecule sized machines are injected into a patient and programmed to build the penis atom/molecule by atom/molecule.
Gene therapy, in which your genetic code is either reconfigured to grow you a bigger dick, or you are given special, geneticly designed drugs which overide your genetic programming, so that your penis’ growth spurt in the teen years is not switched off by the genetic programming, continuing it’s growth until the desired size is reached and the drugs are stopped.
Stem cell therapy. Stem cells are the base cells which can be used to make any and every type of cell in the body. Scientists have already succeeded in implanting stem cells into mice gums and growing new teath. It is now believed that within 5 years, treatment will be available for humans to grow new sets of teath at any age. Scientist have also succeeded in implanting stem cells into goats’ knees and rebuilding the tissues which they had previously removed to induce arthritis in the goats’ knees. Healing the arthritis in the goats’ knees. Some time in the future, this technology could be used to regrow the nerves in the spinal cord, so that people who have been unable to walk for years, can start to walk again and actually feel their legs. This technology could also be used in the future to grow a larger penis.