Better get your coin off masterXchange. I'm not sure what happens on Nov. 15th. I would hope they email you the private keys to your coins but you never know. many exchanges just keep the coins after they disappear.
You just need to withdraw your coin, no private key will be given..
Are you from masterXchange? You will probably have to get users their coins. Are you from the USA? You might go to jail if you keep the coins.
What happens to the people who aren't paying attention or on a 2 month volunteer project helping starving children in Africa?
He sent you an email telling the exchange is closing, seems fair to me. I don't believe he will be keeping users coins..