Sure it can! Google could be the only option in Firefox. But that's not the case. In any case, the vast majority of users simply do not care and will happily use whatever is given to them. The people that do care have the ability to change the defaults.

I'm not really sure why you're viewing this as the end of the world, especially since all the money that Google pays to Mozilla enables the development of Firefox in the first place.

What else are you gonna use? lynx?

Please don't challenge Google in that way.