There is a great deal of progress being made with tissue engineering and organ replacement via a number of sources. Either by taking genetically modified pig organs or by engineering organs from a person own stem cells.
These approaches and using young stem cells to replace old cells in various locations are heading towards replacing more and more of the body with younger cells. This intuitively would seem to be an effective way to extend lives if the procedures can avoid any harmful effects of replacing the tissue and cells.
By being able to repair or regenerate the spinal cord it would be possible to perform whole body donations.
A whole body donation would be something that is technically feasible but unproven and very expensive with a lot of work to overcome or prevent the damage.