Blizzard are successful because they created the first main-stream, polished MMO.
Blizzard was already incredibly successful before World of Warcraft. The foundation of World of Warcraft is the brand Blizzard started to build in 1996.
MMOs are the future of games exactly because the server component cannot be pirated.
I'm not sure what you mean by this. There are tons of private World of Warcraft servers. And you can be sure the same will happen for Starcraft 2. It's the social aspect of the server, not the server itself, that can't be pirated.