Husky wasn't the first to cast. Guys like Day9, Artosis, & Tasteless cast too, and are quite popular. But HD & Husky were the first to focus mostly on "Virtual" tournaments. The other successful casters focused more on "Real life" tournaments. Artosis & Tasteless even went to Korea for a year to comment StarCraft II games on GomTV. Day9 regularly travel to big tournaments.
And yet, none of them make as much money as Husky & HD (supposedly, I don't have hard numbers.)
It shows the power of the web. The old medias are here to stay, but most of the creativity & growth today comes from the web.