I predicted 350k-400k for a full week, but with all the hype I wouldn't doubt if she did that in 3 days. But 500k? Don't think so. Then again, I'm not a Billboard expert.
I think 350k would be a good number, and she'd have a good chance to hold #1 for a second week if she debuted at #1, because the 3-day plan was a great idea in the end. Enough hype already, gets it at #1 early, then Grammys which gives it MORE buzz, holds #1, and by then everyone would have known about Born This Way. And if #1 on iTunes within 5 hours isn't a sign, well damn. I don't know what is.
That'd be amazing if it hit 500k in 3 days, though. Fingers crossed.