Consider how long it took PCs to reach the same stage (with a fraction of the adoption). It was like 20 years from Kenbak-1 to the 90s PC era.
By 2014, everyone had a smartphone.
One barrier to innovation here is that most of tech has shifted to think of empowering users as not the goal, but rather, empowering users is an occasional necessary step towards the company exploiting those users harder.
We could use better thinking.
IMO the iPhone was the 90s PC era where these things got a lot better and more ubiquitous and less fragmented.
And (also in my opinion) coincidentally 90s led into an the era where overly dominant OS vendor(s) were crushing the fun and freedom out of computing. Phones are harder to escape from that than with PCs though.
I think people are not yet ready to accept the exact same thing is about to happen to cars. Some company will have a perfectly usable electric self-driving vehicle and will produce tens of millions of them a year. They will be an appliance, like your toaster, and nobody will care anymore.
I'm sure it will happen to other things in our lives too.
It was a great mobile computing experience but terrible at being a phone.
1. Dialing in the dumb phone. No dumb phones support CardDav syncing.
2. Very few dumb phones can function as wifi hotspots for the e-ink device.
3. Few dumb phones can record calls.
4. I forget what eight was for... seriously I had one or two other issues but I don't remember what they were.
I do believe the future you outline will happen but IMO the timeline is very far from clear. Significant challenges remain for self driving cars.
I was disagreeing with the claim that PCs took longer than smartphones did to reach that plateau. They did take longer to reach the initial (Win95/iPhone) take off point though. Smartphones spent less time in the primordial phase - probably more a case of better internet availability though.
I think PCs still have revolutionary improvements, not only tiny incremental changes: huge core counts, tensor cores, ray tracing, SSDs, etc.
But I'm someone who is still using a pixel 3, so maybe I'm just trying to make myself feel better about purchase I need to make because my phone's battery is pretty close to useless.