Cell phone companies and other major corporations surviving in a world where the economy and most governments are non existent for 30+ years? That's pretty ridiculous.
It's not really that ridiculous. Consider Anheuser-Busch, which survived through the Prohibition-Era. They simply stopped making beer, and started making other stuff in the interim. Likewise, lots of Japanese companies survived World War II, and German companies didn't disappear during either World War, either. A strong company will adapt.
Nintendo is a prime example of adapting your niche; they've been in business since the late 1880s... yes, I said 1880. It wasn't until recently that they started making video games.