Yes, Ethereum Classic is still traded (although I have no idea how thinly). That's exactly why it's a problem: every account pre-fork now exists on two blockchains, and it's not clear what the tax, contractual, legal, etc. ramifications are of essentially doubling everybody's money. The nature of the blockchain also means that forks are destructive against innocent transactions: users doing "business as normal" who have the misfortune of being included in or after the rollback block have to re-coordinate all of their work.