The themes underpinning the Emo revolution will never go away. They will always be prominant feature of mainstream youth culture. Emo, as a catch-all phrase, will eventually phase out and be replaced by a new word-of-the-day befitting the emotional character of the times.
The term "scene" has become popular since the emo subculture kicked off. Scene kids or scenesters I believe are more about the style and looking like an emo without the personality of it all. In other words, scene kids are the ones that dress emo, but only because it's a trend or you could say Scene is Emo without the emotion. The term is subject to a significant debate like emo though.