like you come to a hairdresser's or to a plastic surgeon's office you will come to body modificators, and say "i want to have this. for starters give me a base set for immortality " and he will say "Ok, first you need a second heart, alternative breathing system... " modern day medical and genetic achievements make wonders i think it will be possible to change bodies in the future, like clothes the only body part that can't be newly reproducted is the brain 