The cloud as a computer memory tier

Is it time we stop thinking about the web as an external entity, and instead start thinking of it as a new layer of computer data storage?

What kind of doors does it open if we assume a persistent, reliable connection and treat 'disk' as more of a caching layer for the vast amounts of data available on the web.

Just as RAM and hard disk have their own performance considerations, I think this new layer could be characterized via the following set of properties:

• Read-only (or maybe read-write on servers you own or limited write capability on sites offering some kind of web services)
• Volatile (really depends on which sites are hosting the data, but in general probably don't want to assume that whats there today will also be there tomorrow)
• Virtually unlimited storage (and ever-expanding),
• Extremely cheap (free, subscription, or pay-per-byte)
• Very slow (but getting faster)
• And finally: intermittent failure

There's an emerging set of internet services popping up that are making a more read-right flavor of this cloud-based storage tier which would probably also address the volatility aspect.  Will be interesting to see where this goes...