Good for Apple for trying to stay a step ahead of trouble.
As for everybody moving to some cloud-based storage solution, it's not going to happen. I'm sure it'd be great, if everywhere you go you're either wired or under a cell tower, but you're talking about a very small percentage of the overall user base. ...city people, and relatively stationary ones at that. Primarily, kids. For everyone else, keeping their data far off where access is fickle is pretty impractical.
...beyond security, all this simultaneous network traffic is gonna start requiring a lot more bandwidth & power. As it is now, our wireless networks can barely handle a skype call, much less netflix playing simultaneously and a kid trying to do his homework on the web in the other room.
Though I wonder, if you're Apple and build a data center to store everyones personal files, but also commercial music and movies, do you store the same movie 100,000 times? Or just store it once and give everyone access to it? Hmmmm...