it's a baseless point. i think that if anything they are just saying it to get people more excited. they mentioned no reasoning or market analysis to come up with that number... all they did was pull it out of thin air.
i could just as easily say "bitcoin could one day reach 1 trillion," and it wouldn't mean much if i didn't cite my reasons for why.
US: Hello, China. We like to make another loan.
China: No problem! How many bitcoins would you like to borrow?
US: What's the interest rate?
China: Zero! Just pay back the exact amount of bitcoins we loan you and you're golden.
US: Can we repay you in dollars?... Hello. Hello! Helloooooooo!
US: Hello, FBI. We would like to borrow only $1B of the money you have from DPR's old account, and we promise to pay it back with dollars after the trial.
FBI: No problem. We'll simply call Mt Gox, where we stored it for safekeeping, and have it transferred probably within 24 hours.
US: You guys are the bestest! Wait, what. Did you say Mt Gox?