You have jumped squarely on the industry pundit bandwagon for this column.
Online storage is much more expensive than local hard disk.
Bandwidth is still insufficient, and will be a for a long time. Security is questionable. I cannot imagine restoring my 30 Gig of data over a 768kbs link. I cannot imagine restoring 5 Gig of data. Online archives are a good idea - but have not matured yet.