A thousand of my server on it's "1Gbps port" would about use up the 250Gbps and 16,000 of them to use up the 4Tbps rack.
If you put 2 x 5 disk RAID5 with 2T drives, that's 256000 Terabytes via a 4Tbps rack, using maybe 4 mega watts of electricity.
You could maybe cache all of the useful bits of the Internet on that?
If Users had 20Mps download... that would be 2 Million simultaneous users to eat your 4Tbps rack.
At typical levels of traffic/contention (as people take breaks to sleep, read the content etc) you could supply a largish country. Or a small one with peak time true HD quality VOD.
Who are these 4Tbps racks for?