This Hack has nothing to do with Nem being hacked.  Only the exchange was hacked.  Coincheck had their private keys stolen.  CoinCheck did not use the multi-signature features that the Nem Blockchain offers them.  CoinCheck Claims they were short-staffed engineers.  They had all of their nem stored in a hot wallet.  They claim they were in a process of moving it to a cold wallet.  They were unable to confirm the hacking of any other currencies at this time.  They are considering compensating all the customers that had nem on the exchange.

http://cryptonewsflash.com/coincheck-hacked-for-523-million-nem/