Bing already pays for users, and once you give it time to build up a profile of you so it stops returning reptiles and vegetables when you're trying to search for Python libraries, it's equal in quality to Google. If having a high quality service literally give you things to use it doesn't break Google's stranglehold on search, what will?

I think the default for some time was DuckDuckGo, and that helped raise them out of complete obscurity, but it didn't reshape the internet landscape.

I'm pretty sure a lot of companies would pay a lot of money for that.