Dave Lee thinks we're near the end game for smartphones:
https://www.youtube.com/watch?v=otHviixLykI
I think so too, and I've heard similar sentiments from other people in the tech industry.
...but, oh my god, look at all the idiots in the comment section. All the complaints about smartphones being too expensive. That's literally what a high-end phone is and why the market's moving toward mid-tier phones, which was the whole point of the video...