From where I sit, it all this "unifying the edition" talk is boilerplate for bringing the 3.x and 4e crowds back together. I'm sure they'd love to bring OE, 1e, basic, and 2e players back too, but really those groups are too small to be the driving forces behind all this. This is about Paizo and Pathfinder, and bringing those people back to the D&D brand. If 5e does that, it will be commercially successful. If it doesn't do that, it will be a commercial failure (from Hasbro's perspective, which is the only one that matters). In order to bring 3.x players back, you need to make sure our views are championed thoroughly at every stage of the development and marketing process. We don't need to get our way on everything, but we do need to get our way enough to make it worth our while to turn our backs on a company most of us like a lot (Paizo) and a product that most of us are quite satisfied with (Pathfinder). That's the stark commercial reality WotC is facing, and Cook's departure makes that a bigger challenged than it already was.