If you had massive amounts of bandwidth available in a datacenter, but for downstream-only, what could you use it for, commercially? Most providers of content have to buy large amounts of bandwidth, but it’s for outgoing traffic only. If there were a way to use the incoming bandwidth effectively, it would essentially be free.
You could provide backup service (where people backup over the net TO you), you could provide bandwidth to end-users (who download mostly), and, well, that’s all I can think of. What else is out there?