I have been on this exact same quest and train of thought recently. I agree with almost everything you say about current UI elements sticking around. However, I do strongly feel that UI may be on the brink of a new revolution and we just don't know how it's gonna look and who's working on it.

Xerox Alto was the first GUI ever (ironically I chatgpted that in a text based interaction :D) and the leap from text to GUI was really not that obvious either I would think. I think we're in the text based computer era now and can't just know exactly where we will be in the next few years.

Now here's my crazy idea that will likely put me in a mental category: I think the ultimate "UI" will be intuition. It's not that I ask an AI to do something or fetch whatever I want. It's the act of just having constant access to all information and action subconsciously. Now for that you'd have to wait until Elon plants a chip in everyone or someone comes up with a less dystopian device :D

If you ever get to more clear answers to your questions please do share. Like I said I am very curious about this topic.