Do you really think Google's going to say in a few years, "well, this AI stuff was neat but we're going to sunset it now"?

AI, no; this AI stuff, almost certainly. It's kind of like arguing that Google's never going to give up on chat - sure, chat is important, but that's not exactly helpful to the devs who made use of the XMPP interop in Google Talk to build great apps that then broke when Google killed it.