I wonder how far you need to go before a brain transplant is cheaper / safer than replacing it. I can see replacing major veins as being doable but capillary's are far less so.
Sure, we can; but if we'd thought that way before we would never have developed medicine. For some reason in every generation there are people who seem to think that using the medical science they are familiar with (or just slightly less) is okay and normal, but using anything more is somehow contrary to nature. But using our mind to develop new ways to overcome the limitations of our bodies is our nature just as much as the failures of our bodies are.