Considering the comment by the OP, the question is:
Would replacing healthy organs with replacement organs be beneficial, using current technology.
TheIf you're looking for a science based answer, the answer is unequivocally no. No current mechanical organ replacement gives as much of survival benefit as an allotransplant (organ transplant from another human). These devices are at best a bridge to transplant in patients who are healthy enough to get a new human organ. Additionally, allotransplant is unequivocally worse than keeping your own healthy organ. It is even worse than keeping a not particularly healthy, but not quite yet failing organ. As a rule, we try to manage unhealthy organs medically for as long as possible before even considering transplant. The major problems here are rejection and vascular events, or the problems that result from treatment of those problems, bleeding and infection. Organ failure (of the transplanted organ) is an issue as well. A new organ can feel like a new lease on life to someone who, for example, has been in stage IV heart failure, but it comes with major challenges. To use the metaphor a few other answers have used, OEM parts are best (human organs), but a replacement part of any kind is not an upgrade unless the original part has failed.
You can read about this in Schwartz's Principles of Surgery, Chapter 11, if you'd like to learn more.