Although your facts are wrong, it will indeed be a big hit. There are no sub fees, but will have micro transactions that Blizzard will be making a haul off of (farmville anyone?). Most investors do not realize this game was slated as PC only, but will likely make the transition to console as well. Its a console laden world and Blizzard just spent too long making it for Kotick not to maximize its value.
Diablo players /= to Farmville players. Diablo players will be very resistent to micro transactions and extra fees. Also, Diablo is not as big of a franchise as Warcraft. I would be surprised if it sold 4m copies lifetime. I seriously doubt that it will break 3m.
You sir are ignorant. D3 will sell 5M+ by end of 2012 and the micro-transaction will make so much money. Why?
D2 sold about 4M+ .... how many years ago? Do you know how much larger the PC gaming industry is now?
D2 release in 2000. The franchise isn't warcraft but it is extremely large.
Not to mention micro-transactions are a trend that isn't being resisted. Hell technically there was micro-transactions in d2 but they went from player to player illegally. Don't believe me?
Look at league of legends SUPER POPULAR and uses a micro-transaction base. I know many players who have spent upwards of 100+ on a FREE GAME. Surprisingly it is more odd to not spend money then to spend....
Keep in mind everyone who has played WOW will most likely at least try D3 purely because its a blizzard release in between the next WOW expansion.
However my one worry is how Blizzard plans to "reset" or create expansions, D2 would reset every few months allowing a clean slate for everyone to build back up again. Now question is how to manage that. One side says Reset every 6 months because this will erase the in game items purchased with microtransactions which will create more microtransactions next 6 months. But this could be annoying to user and upset them. On the other side you could release new patchs with new gear which is better.... making new transactions. All in all I am not sure how they will do it. But its a major factor for the future of D3.