A more plausible scenario would be simply that the cloud company you chose for your data (and applications, if you dared) just decided one day that they didn't have any more money, turned off the power, and walked out the door. It could even happen to Google some day.
Actually, it already did...Google+ shut down its consumer accounts last April. Tiny Pic (owned by Photobucket) shut down in September, citing declining online revenues. But I wouldn't discount the other scenarios, either.
There was a year when HC was hacked. It didn't really matter, because there was no information stored about people other than their email and password...no credit cards or anything. I was curious how common this was. I was shocked to find out that 400,000 sites had been hacked that year, including sites like the Department of Defense, the British government, pretty much all banks, etc. etc. There is clearly no defense against people who have skills. So far, there have only been a few incidents that came close to bringing down the internet, but they were uncomfortably close calls.