I think they are banking on generative AI displacing traditional search of all types, maybe opening a few new related doors but mostly displacing large use cases of search. "Better enough than Google to convince users to switch" was always too high a bar to meet but being able to say "How do I take the Riemann middle sum using the points {1/2, 1, 3/2, 2} for f(x)=x^3+2" and getting a response built around your specific question instead of the best generic link talking about Riemann sums is definitely the strongest contender I've seen to finally meeting that bar. Users don't want to find the best page about Riemann sums, they just want an answer to their question.

The challenge will be "does it do that well enough, accurately enough, and keep a good enough lead to establish itself as the leader to beat for the user base".