Sure, but I'd imagine that most email traffic is automated non-sensitive stuff (i.e. flight confirmations for example). That stuff is simply not going to be e2e encrypted any time soon, if ever.

Are people going to start filling in their pubkeys when they book a flight? What about when they're at the airport and need to pull up the record locator on a different device?

I'm sure more emails will start being encrypted, but that'll mostly be communications between people. Those probably aren't particularly interesting to google anyway.