Personally, I don't really care if they ever ship a working AI feature as long as they don't neglect and shittify the rest of iOS/macOS in the process.
I wish they would forget the really advanced features and just focus on little ones. Like particularly with Alexa back when I used to use that, one of the major frustrations was figuring out the magical word order that would get it to do what I wanted, it would only do a thing if I said it in a certain way otherwise it would get condfused or do the wrong thing. An LLM would be great at making that not happen.
But instead of just that little bit, they're trying to do Star Trek levels of computer voice control, missing out on incremental improvements.
Alt-Tab doesn't show window previews because it switches between apps and not windows. Previews are in Mission Control which is for switching between windows.