If hackers can performed 51% attack regardless if it's ETC or not, chances are they are going to do it again and again. It's just a matter of timing and of course how much money they can generate in this double spending attack. I don't think you can lose your funds though in a 51% attack. But if you sit your ETC on a wallet that has been compromised, then definitely hackers can steal it as well (and so are the other crypto wallets).