I think they will come back. Maybe offer users no fee for a long, long period of time to recover this loss.
That service was so widely used and I don't think they ll give up on that. Just wait and see, they did say 24 hours.
Sorry to say I've been mining since 2013 and i've never seen a "hacked" pool return funds.
They will not surely cameback since how could they refund the funds of their investors for this matter? The what so called hack amount is big and that is totally made the nicehash became emptied and I think this scenario can make their business closed, But we should be more optimistic on the other side since theirs also a possibilities that maybe they are decide to scam their investor since they've see that the price of bitcoins soar high and their operation is not profitable for theirselves.
It is not only Nicehash, but
hashflare.io is also about of service. Could it be related?
Well maybe and if hashflare gone well a huge lose for all of the investor who believe on both legit cloudmining site wanna be.