The big breakthrough science needs is figuring out how to shut down the POV we have without making us unconscious/dead. Basically, how can one be converted into a P-zombie, and back, without causing unconsciousness or death in the process?

Or put in another way: What is the minimum amount of brain required to transfer my consciousness, and ONLY my consciousness (not including memory, language, knowing how to walk, etc), into your body?

Figure that thing out, and a lot of before and after questions become easier to solve.