Quite an achievement, with such fierce competition. And I said Heartstone doing so well is ironic because I don't think Blizzard foresaw it'd become such a thing. It was probably put together by some MTG nerds at Blizzard during lunch, the basic version at least.
Regardless of how much competition SC2 has with other rts games (it does have a few), it would still be wrong to call it dead, simply by comparing it to the biggest e-sports games of 1 particular genre, the moba genre.
Regarding Hearthstone: I think on the contrary, that Blizzard was well aware of the unexploited potential of the digital card game market.
If you think Blizzard makes their games out of blind luck or just a hunch, you are mistaken. Blizzard has ALWAYS have been great at analyzing the market, and coming up with products that offer something different than what is currently being asked for.. (or coming up with someting that doesn't exist). Isn't that what all the great innovators are doing? Isn't that also why apple became what it is, today? Doing something you've seen before, only better and more "acceptable"? Filling a need, nobody knew was there, but it was?
You might not like Blizzard games, you might disagree on how they run their business and such, but there's no denying that they have a keen eye for spotting potential and using that to their advantage when the time and circumstances are right.
They did it with basically all genres of games now. FPS, MOBA, RTS; MMORPG, Platform
All they need now, is to make a real cRPG
.. That would be interesting.