Forged in the Barrens Cards List & Guide
Will classic mode have only classic and basic set forever or they will add older expansions like Nax or Blackrock and keep going over time ?
Not been confirmed either way, but they are open to the possibility. Don't count on it as a given.
Curse of Naxxramas, which was the first "expansion", added many powerful cards.
I think standard is more fun without Sludge Belcher and Loatheb for example.
But if it happens a year from now I would probably be for it.