This was already discussed by Heartstone Devs, and still, about the possibility for some cards to go to the Classic set. Cards originally part of expansion being moved to classic and be played at standard forever. But remember, we can't just ask for our favourite cards to be moved since i has to make sense in a game plan perspective.
My question here is: What cards you think are most fit to be moved to Classic since the first expansion?
I didn't find the right solution from the Internet.