More and more people switching to DuckDuckGo as a default and using Google only when necessary would get the ball rolling. Gmail is pretty replaceable with any other email, although I can see many people not changing from it out of laziness.
Google drive apps are pretty nice, but I doubt most people use them much at all, and Microsoft/apple offer alternatives. Google maps can eventually be replaced if people started using the alternatives more.
It will take time, but seems doable if more and more people keep changing habits.