I don't know for sure, but most likely they are lost forever. That's very unfortunate for all those people still holding coins on their exchange. Even if that are shitcoins they should have been allowed to withdraw them to a wallet they control. I myself had some very low amounts of ETN (not that I consider ETN a shitcoin), trading it just for fun, so I'm not really affected. But I can imagine people holding there huge amounts of coins, which would translate into huge losses.

Just another case showing us that exchanges should be used either for a quick trade, or you should put there the amount you are comfortable losing.