Blizzard could easily make millions by selling more pets and mounts through the Pet Store, but they don't. Why? Because they probably feel it'll be healthier long-run (and thus better for the long-term profitability of WoW) to not make too much premium content. So I disagree with the implicit assertion that they'd never leave obvious money on the table.

Similarly, a RMAH isn't actually that much of a cash cow. Consider the fact that fees are probably going to be very low - I'd guess in the single-digit cent range - in order to not push out too much business. Consider also the additional cost of the servers to run both Diablo III and its RMAH in a secure and backed-up manner. Consider finally the fact that DIII has *no monthly fee* - the RMAH will probably make back their expenses for keeping the DIII servers up, but the idea that Blizzard will be generating tens of millions in profit is nonsense.

There's no binding in Diablo. You get an item from someone, you use it, you resell it when it's upgraded. As Blizz said, there isn't so much of a prestige value. In WoW, there's a concept, not just of upgrades, but of progression, so they'd definitely never make the majority of raid drops salable the way everything is in Diablo. Because the only items being exchanged for real money would be entry-level items, profession mats, and gold, I don't really see that much revenue being generated from it - not compared to the trade in high-level uniques and sets that will be DIII's bread and butter.