As to games, remember Age of Conan?
What's your point?
For one thing, AoC is still around and kicking, including an upcoming expansion. As far as any of us knows, it may be a financial success by now, even if the player base has shrunk.
For Another, AoC is a Funcom game, no relation of Blizzard/Activision. Which of course brings us to your next point...
Blizzard appears to have a pretty good hit/miss ratio so far
I think @gravos' sentiment, while badly worded, is correct. Blizzard seem to be really good at what they do and presumably the "cut-scene filler" will actually be something that helps sell the game. As for "pretty good hit/miss ratio", it's pretty darn fucking spectacular, calling it "pretty good" is just about the understatement of the year.
but it's hard to say if it's luck, talent for seeing what will work, or just hordes of loyal fans.
Luck is getting 1 hit game. Smash hit after smash hit implies something more.
As for the "hordes of loyal fans", I guess you're implying that no matter what Blizzard does, the "loyal fans" will buy and cheer? Just look at the recent RealID on forums fiasco and outcry on the WoW Forums, fans were certainly not shy about letting Blizzard know it messed up there!
So I don't buy it. I think Blizzard really are good at taking a concept and making a best seller game of it. I fully expect SC2 to both sell well and get good reviews (relative to the dated graphics it uses). My only personal complaint is that the game is expected to sell for I think $50 and will open only the Terran race in the single-player story mode, which means $150 for all 3 chapters and who-knows-how-long-to-wait for the next 2 chapters. To be honest, that's too steep for me, I'm going to sit and wait till prices come down and hopefully parts 2 and 3 are released.