I also have lots of ideas, not all that different from the goals of some of these... but there's something critical to remember. The terminal survives as it is, because so many tools were built to run on them. They are only becoming more cross platform and feature rich, albeit slowly and conservatively.
Maintaining a high level of backwards compatibility while improving the user experience is critical. Or at least to me. For example, my #1 fristration with neovim, is the change to ! not just swapping the alt screen back to the default and letting me see and run what I was doing outside of it.
We generally like the terminal because, unlike GUIs it's super easy to turn a workflow into a script, a manual process into an automated process. Everything is reproducible, and everything is ripgrep-able. It's all right there at your fingertips.
I fell in love with computers twice, once when I got my first one, and again when I learned to use the terminal.