I remember when I first got Warcraft 3, it was very fun although I had no idea what was going on at first lol. I was total nub back then, like 'leaving Acolytes to finish their buildingz' kind of nub XD
Then a friend showed me the World Editor and liked to show how you could set units to have insane amounts of health and stuff. Of course, I never particularly cared for making units op intentionally, so after a lot of doodling around with the melee races (simple things like making campaign units available and such due to a natural love of the unobtainable), I finally started making some new races of my own. Although they weren't any good, it was fun to find out more and more about the Object Editor, especially considering I couldn't Trigger for shit and found Terraining to be boring and tedious on the most part
However, I am now working on a big-ish project called 'Settlers of Rahgaer', where you deploy unit squads at the start of the match after choosing one of the many FPS inspired gameplay modes (e.g. Deathmatch, Timed Deathmatch, Control the Points, etc.), and I intend on completing it for Warcraft 3 players everywhere.
The point of the matter is that even though Starcraft was much more successful in terms of gameplay than Warcraft 3 ever was, Warcraft still has a lot of history with us and still has a lot of interest in terms of modders. And besides, it's not like everyone's going to instantly convert to the SC2 editor as soon as it comes out. I mean, most people will experiment with it, yes, but most maps will probably be put on hold until a decent variety of custom models come out for it. And even when they do, Warcraft won't die out completely.