In a word, no.
Warcraft's current style is so intrinsic to its identity as a MMO, in my opinion, that it wouldn't be the same if it changed to a more "realistic" style.
You know what other two MMOs I've enjoyed, stylistically, recently? GW2 and Rift. You know what I enjoyed most about them? The more "cartoonish," very brightly colored landscapes and races.
"Realistic" graphics don't age well at all, and they tend to look very... uncanny. I don't care for them. I don't care for the look of things like Skyrim at all, I assume that's what we're going for when we say "realistic?"