I've always loved blizzard games, at some point though you need to let a franchise run its course, end the story. You don't need to continue it just for the sake of longevity.
Riot has had some amazing success with League of Legends, many from that original founding team, were creators of DotA a mod for WCIII.
Rather than working on a mod for Starcraft to include their DOTA ALL-STARS. What if they created a brand new franchise, a new story, using the moba type of game?
I think it would be a great success.