The existing exchanges don't guarantee wallets' usability. Once exchange closes down, your wallet will become invalid as well.
However, Tettix takes Metamask as wallet, which means you can keep your wallet's private key and no need to worry about its usability. Now, join Tettix and be your own master.
Tettix is creating a REAL decentralized exchange. Our goal is to remove redundant constraints on digital currency transaction.