If the overly optimistic upside is a quicker, more knowledgeable, higher-performance-information-digesting personal assistant at lower cost than ever before, it

If the overly optimistic upside is a quicker, more knowledgeable, higher-performance-information-digesting personal assistant at lower cost than ever before, it would still be out-of-reach for almost as many ordinary people as the top professional human personal assistants are now. Unless they never manage to reign in the costs, then it will be more out-of-reach than a real human, disregarding the potential game-changing element of real human empathy. I would expect those that have funds to spare already have both, regardless of the limitations of each. If you can come up with a possible downside, that would be something to compare it against. Everyone might not have to be cynical for their opinions of the potential outcome to be either positive or negative.