Delisting STEEM on centralized exchanges does not affect STEEM anymore (or at least not much). SteemEngine (although centralized too) has created quite a great deal of independence on STEEM. Many Peg's made possible what it might be later become a decentralized Exchange (something like the BTS DEXes...).
Yes you still have the gateways to solve... but way better than a fully centralized exchange (even if it has its front end on the cloud).
RE: Poloniex Exchange To Delist STEEM Alongside 5 Other Altcoins: What Can Be Expected in the Few Weeks Ahead?