You won't have to worry about storage by then, surely everything will just be pumped straight in to the cloud and sucked back out to view it all in a thousandth of a second
I will never trust the cloud to store my photos. I won't put my photos in someone elses hands. I need to be responsible for my own stuff. That is the only way I know it's safe.
While I would not simply dump it into any cloud I can assure you that the pros can keep your photos much safer than you can. I work in the business and the technology we employ to make sure your data is kept save is not affordable to the average joe. Of course that service comes at a price, but I would certainly trust my company much more to keep my photos safe than I could ever dream of.
Multiple DC locations equipped with the latest and most reliable backup hardware solutions, automatic duplication of any backup image into at least two locations. Fully automated validity check of the data with automated fail saves that will recreate a second copy should either one fail. And of course a migration path to make sure all data is moved onto the next hardware generation once it is being employed. (So no sad faces that there simply are no more 5 1/4" floppy drives out there)
Just like with photography it really depends on how much you are willing to pay. You can have your job being photographed by the guy with the disposable camera for free or pay a pro several thousand $ to make sure everything is perfect.
In 20 years time I would expect to have RAID datacenters with storage clouds that are self replicating you data over multiple locations. This being integrated right into your own devices to be viewed and worked with as you want. You wont have any more localized storage since this simply does not make sense when your dSLR will have full internet access to write any image you make right into your own private cloud space, instantly accessible to your laptop and all other devices for sharing or processing the image or even to integrate it right into your dA, Flicker or FB account.