Not all clouds have silver linings …

AaaS/StaaS (Archive as a service, Storage as a service) seems to have providers dropping their offerings as they are not very profitable.
As with computing as a service, the issues are costs, pure and simple. For this to work well as a service, you, the provider, need your costs to be well below what you charge your customers. Moreover, the cost you charge your customers needs to be below their entire burdened costs for replicating the same thing in house.
Exactly like all other *aaS models.
For some providers, it is. Start with inexpensive and fast/reliable storage, and build them up in clusters. Then use iSCSI or similar block devices, with encryption, and volume management layers to provide replicated/secure storage. Or use something like Tahoe-LAFS for this.
Or select other vendors really expensive storage, not get enough customers to meet your higher revenue requirements, and eventually leave the business.
This is the 3rd iteration of ASPs. This one may finally, really take hold. But not every cloud will be profitable. Not everything should go into the cloud. Not all clouds should be public.
At a minimum, while planning for clouds, a very real, and very important question to ask the vendor is, what is your transition plan in the event of a business event (change of business, bankruptcy, etc.)? If you build a monoculture based business dependency upon a single supplier, even for your clouds, with no recourse to easily move to another provider in the event of an issue … then its your fault if their business changes negatively impact your ability to operate as a going concern … with all your business data sitting cold, idle, and unpowered.
Various best practices seem to emerging for clouds. One of which is you do need to replicate across multiple different players as well as multiple geos. You shouldn’t rely only upon one, as the risk to your business may be very high. Asking hard questions on the providers financials won’t help either … business events happen with great rapidity. You need to be flexible, able to adapt, nimble. If your committment to one vendor is too large to move … you have failed. As the provider won’t last forever, and the line of business might not either.