It all depends on the supply-side, because the *DEMAND* is always spectacular. If there's a shortage on release, which there always has been, you'll make a profit.
BUT, just because there has been a shortage in the past, doesn't mean there will be a shortage in the future. The supply is controlled by the console producers, and they can see how much money people are willing to pay for a new console. Historically, nobody's been able to produce enough to satisfy the demand, but they're making more and more every year, and they're getting better and smarter about the marketing.... someday the gold mine will run out.
Well they aren't stupid, they relay on the consumer feedback.