I'd be interested to see how well an AI, trained only on the outputs of an individual, would be able to mimic that individual. Getting into Black Mirror territory. Would need a decent corpus of learning material which, personally, I'd be loathe to spend the time and effort creating because I respect my own privacy.... which then leads to the only human-clone AIs will be of those people who have enough ego / arrogance to want to catalogue their own lives, which could put a decent percentage of the rest of the world off the idea, if these are the examples.