If in future, you are able to change your internal organs in order to renew many chemical interactions of your body that will make your appearance and spirit like only 20 somethings--the brain must not be replaced--will you do it as medical cosmetology? Which means despite you are 80 old, your body functions as baby newborn because all of your organs, except brain, are changed deprived from stem-cell cultivation. Thereby making yourself probably look 40 something.
If it's me, I will do it. I want to live over centuries to see how people evolute.