Note new
Good heavens - network storage and backup services have been available to ordinary folk in the retail market for years. There are even some free ones around and often associated with ISPs.
The biggest problem for many people is that the broadband networks aren't up to their requirements. Upload speeds, especially, are far too slow for many of today's multi-media files. Of course you can use "in-the-cloud" services and do your photo or video manipulation there, but you still have to get many GB of data uploaded in the first places.
If/when there are broadband networks with upload speeds in the 10s or 100s of mbps then this market will really take off. For the moment it;s stuck on bandwidth limitations.