I would say Google has a couple of fairly uncommon requirements: ridiculous scale and the fact that even a brief outage is world news.
In terms of "rewriting all this software", I wouldn't say it's at all for the sake of switching to Go. It would be more accurate to say "well, we need to rewrite this thing anyway because it's no longer scalable or maintainable. Let's give Go a shot instead of C++/Java)"
Fairly uncommon compared to your everyday website sure. But I can think of hundreds of companies that have ridiculous scale and brief outages would be newsworthy:
Airline bookings, Stock exchanges, Betting markets, Postal services, Major websites (Facebook, Twitter, Pinterest, LinkedIn), Online Games, Video services, Payment gateways, Banks etc.
Scale in and of itself isn't the basis of a sufficient argument though. You can write software at that scale in Visual Basic if you have billions of hexcore machines at your disposal.
In terms of "rewriting all this software", I wouldn't say it's at all for the sake of switching to Go. It would be more accurate to say "well, we need to rewrite this thing anyway because it's no longer scalable or maintainable. Let's give Go a shot instead of C++/Java)"