There are cases as I believe you have shown of people living with large portions of their brain reduced to a much smaller size. This shows that a person can remain a person even with loss of brain mass. Also a computer can serve a normal user as a proxy memory holder. Or with the internet an uneducated person can google and at a moments notice learn anything that they desire. Meaning that technology is becoming a proxy method of our brain. Say we took a machine and hooked it up to a person that is living and quit healthy with a good brain and mind, and extended that persons brain power. Say that said technology progressed to the point of complete brain-machine interface. And say that the machine portion was better equipped for the purpose of our body and we eliminated most of the brain to accommodate the machine within the skull. perhaps even to the point that the brain truly only takes care of bodily functions.
What are your thoughts on that situation? Can the brain be slowly removed and replaced by a machine one cell at a time until there is no organic material and maintain to be the same person? If you believe that at some point the person would die at what point would that be? or on the other hand if surgeons replace portions of the brain with lab grown brain and those pieces completely integrated with the original brain tissue. Which it has been shown that the brain can regenerate cells and rewire portions of the brain when needed. Conceivably the new tissue would work the same as the old tissue. If we slowly replace all of the old tissue with new tissue letting the brain slowly adapt to the changes would that person remain who they were and aware of it?