I notice in your hot tub Harry surgery experiment you leave Harry’s brain AND skin receptors in the water. Is it your contention that if his skin receptors had also been removed he would no longer be conscious? As I read your post you seem to be suggesting, though never outright say, that a requirement of conciousness is the ability to have/feel sensations. Incidentally I have great sympathy for this view and believe it to be (mostly) true. I simply see no other way to avoid committing the mereological fallacy when considering the phenomena of consciousness in beings such as ourselves. But that is neither here nor there.
Continuing with our friend Harry, why leave his brain/skin receptors in the hot tub and remove his body. Why not leave his body and skin receptors in the hot tub and remove his brain? This is basically asking the same as the above. Is a brain without access to sensation capable of conciousness? If your answer is no then why are you so optimistic about the possibility of artificial intelligence actually being/becoming conscious (I believe you imply that possibility in the last part of your post). Have we figured out how to make computers experience sensations? I was not aware of that work. Please send me the link to the research group that has demonstrated programming the experience of sensation into a machine. Reacting to environmental stimuli is not experiencing sensation so please don’t send me links to all the robots that can do X in response to Y crap that’s been done a million times. I am only interested in robots that can experience the warmth of a mothers embrace or the tenderness of a lovers kiss. You know, the touchy-feely stuff. If your answer is yes than your hot tub Harry example has lost all of its explanatory power. Either way poor hot tub Harry has found himself in a sticky situation.
Finally, I think you mischaracterize the positions of a host of researchers in the scientific fields interested in this question. In particular, the hard core materialists like Patricia Churchland, whom you mention, object very strongly to the characterization of consciousness as “mysterious” much as you do. They believe that consciousness can ultimately be explained by the physical/chemical properties and structure/function of the brain. Once we have a complete understanding of this, consciousness will be shown to be nothing more than an inherent and/or emergent property of the particular neuronal structure and biochemistry of our brains. Nothing mysterious about it.