I know they will back down, but it makes me wonder; what if they didn't?

Could a business, a corporation, go to war against another entity. Countries go to war all the time and while it may be "illegal", it's only the loser that has to suffer the consequences.

What if Microsoft just decided screw it, and flipped a magic switch somewhere and shut down the entire EU infrastructure. No OS, no web servers, no SQL, no sharepoint, etc. Trashing or stealing every bit of data along the way? Freeze Microsofts assets you say? What if they could freeze or steal a great portion of the EUs assets?

Sure, the EU would get over it eventually, but it's an interesting thought experiment.