This was a really interesting read. I think a lot of this is plausible and it is similar to my own expectations in many ways. Thank you for writing this.
That said, I think your vision is too conservative. AI the field that will change the world massively this century where transformative changes are already certain. But there are other candidates as well. Space development, self replicating macro and nano machines, human enhancement and new physics are options I consider likely in descending order. The interactions between those fields are the truly scary thing. You acknowledge that your predictions are very likely to be false, but I think the biggest error people make when trying to predict the future is that they look at only a single dimension and ignore the interactions. For example, a power seeking AI could reasonably prioritise gambling on an interstellar land grab in the forties.
Another point where I disagree with you is that AI’s will cause more damage with spreadsheets, medical procedures and legal procedures. The human standard is already pretty dismal here, but we are wired to trust people in those positions. I think that while it is certain that AI will fail in some cases, it is far from certain that it will perform worse than the human baseline.
I like your suggestions about the dating site, however, what you describe sounds a lot more like a matchmaking service. Those do already exist but are usually quite expensive. As I understand it, usually they sign on clients for a hefty fee, analyze them, and proceed to introduce them to other clients they think would be a great match. Then the two date and see if it works.
I don’t know what kind of methods they use, but I guess using ML and psychology might be able to reduce the costs of such a project significantly.