> I think it's more like a foundational user interface.

I don't. The foundational interface hasn't been created yet. Let's be honest, chat isn't great. It is the best we have right now to leverage the technology, yes, but if it is our future — that we cannot conceive of anything better, we've failed miserably. We're still in the "command-line age". No doubt many computing pioneers thought that the command-line too was foundational, but nowadays most users will never touch it. In hindsight, it really wasn't important — at best a niche product for power users.

> Apple may have learned a very unhelpful lesson: that Siri is just a feature, not a user interface.

That is the right lesson, though. Chat sucks; be that through voice, typing, or anything else. People will absolutely put up with it absent of better options, but as soon as there is a better option nobody is preferring chat. This is where Apple has a huge opportunity to deliver the foundational interface. Metaphorically speaking, they don't need to delver the internet at all, they just need to deliver the web browser. If they miss that boat, then perhaps there is room for concern, but who knows what they have going on in secret?