Since the data is distributed approximately randomly across all sections then this would be an impossible situation. On the other hand if one or two data centres had that capacity then look up the “google attack” topic for a lot of good discussions about if an attacker tried to do this.
Since one of Maidsafe’s goals is for home farming then I am confident that the reward structure will be such that data centre farming with them having to pay for all their inputs is unable to compete successfully on a global situation against the home vaults with their 100Mbit/s to 1Gbps to 10Gbps bandwidths. So while they could turn a profit they would still be looking to getting income from renting their services out to those still needing them as that would be more profitable. Thus only farming to use their “hot” spare capacity
Also the distribution of home vaults across all the ISPs means that bandwidth clog points are more distributed than massive data centres with 10s or 100s of thousands vaults all requiring usage of their limited number of 10 or 40Gbps links to the backbone Whereas 10s or 100s of thousands of home vaults are spread across 100’s of countries with 10’s to 100’s of ISPs each and their backbones into the internet.