Apple seems to agree that that would be the ideal UX for AI, but for any computer, (1) it's going to require massive rework at the OS level, and (2) app develop

Apple seems to agree that that would be the ideal UX for AI, but for any computer, (1) it's going to require massive rework at the OS level, and (2) app developers have to be willing to integrate with the OS-level AI. I'm not sure that the latter is happening since profit incentives much better align with walled gardens.