My understanding is that Apple's approach to this integration is adaptable; much like how you would change your browser's search engine, you'll be able to change which external AI model is utilized. ChatGPT, Gemini, Claude, etc.
I'm sure there are usecases for this and the other GenAI features, but they seem more like mildly useful novelties than anything revolutionary.
There's risk to this as well. Making it easier to produce low value slop will probably lead to more of it and could actually make communication worse overall.