If anything, Microsoft would just step in to fill the vacuum with Bing, and business would continue as usual for everyone but Google.
No, we're not going to do that. You'll have to shut us down, which will take years, and cost the economy millions of jobs and trillions of dollars.
Oh, and I hope it goes without saying that we won't be complying with any court orders related to this matter. If you're serious about doing this, there will be pictures of men pointing guns at innocent American technicians, right next to the headline "The Feds are Coming for Your Email," and underneath that, Senator, will be your name.
Then they'd say something like: "This is America, motherfucker. Land of the free. You can't get away with this shit."
...sigh. At least it'd make a good screenplay.
You want a big multi-billion $ business to start dictating your laws?
Good luck on that one, that's not going to end badly is it?
The current system, where corporations often actually, literally dictate many laws is a lot less open and straightforward.
From a societal POV, big anything is bad. I wish more open-minded people could recognize that fact.