Its happening quicker than you and i probably realise.
Many of us are still struggling with laptop hard disks that are filled to the brim. We all carry our own USB keys. Many of us have bought unwieldy External USB hard disk enclosures and Network Attached Storage (NAS) that are now an emerging too fill the SOHO market segment.
But all of this is just, a precursor to where were heading. Which is online storage. No need to rely on localised hard disk storage.
Who says this better than Google: "With infinite storage, we can house all user files, including: emails, web history, pictures, bookmarks, etc and make it accessible from anywhere (any device, any platform, etc), .... We already have efforts in this direction in terms of GDrive, GDS, Lighthouse, but all of them face bandwidth and storage constraints today..... the online copy of your data will become your Golden Copy and your local-machine copy serves more like a cache"
Today, the only real large scale provider is Amazon. Amazon's s3 Web Services, provides a pay-as-you-go utility model for buying and using storage over the Internet. Essentially you need to sign-up for an Amazon S3 account, you are provided with your own Access ID and Secret Key for encrypting and decrypting your files on the network. If you lose it then you've lost your files its as simple as that.
Anyhow, i downloaded client tool (which relies on Amazon S3), called Jungle Disk (they even have a Mac client), and use that to connect to the Amazon service.
Its a fairly rudimentary client, but looking at the sheer size of resources behind Amazon S3 (e.g. Microsoft may be outsourcing some of their storage to them and smug-mug pass over 10Tb of pictures through Amazon S3) you kind of realise that this is a pretty sophisticated operation.
Am i ready to drop my iTunes music over into the big cloud, not yet. But its certainly the starting point for me to rationalise and make my content better shared between machines.