Time it takes for BFL to produce and ship 300 500GH/s rigs = 10 months to indefinite
Time it takes for BFL to finish current order chain = 10 months to indefinite
Hashpower increase once order chain is finished = Way more than 300 TH/s
Also, BFL has said that they won't sell enough hardware to 51% attack
So money required to create roughly 50 identities to purchase the 300 500Gh/s rigs? Millions of dollars.