I'm a paid Kagi user (not the API) and one neat feature they have is if you search for something without a question mark, it's just search results. If you stick a question mark on though, it does the quick answer ai response. (this pattern might be common elsewhere, I'm not claiming it's unique)

I've noticed that I'm now getting frustrated if I forget the question mark, as I actively want and prefer an assistant response. I'm sure this wouldn't always be true, but chat is a nice way to do search... and I suspect more thorough than I'd actually be at checking longer-tail sources.

My point is, I think this interface might be what a search engine for humans looks like now.

That is a clever UX, Kagi seems to be very mature.