Both D3 and SC2 took an awful long time to arrive. I doubt any other companies can afford that long to wait between games.
So Blizzard has an big advantage which they use. It would be interesting to read how profitable those games are, compared to the cost to make them.
I am sure companies would prefer to spend 10 million, sell 20 million, making 10 million than spend 45 million, sell 50 million and make 5 million.