When Bitsquare grows to include lending/margin markets and Tether, why would anyone want to put up with Polo's counterparty risk, trading fees, KYC/AMA, and PG rated troll box?
The answer, as always, is convenience and ease of use. Bitsquare requires users to run their own wallet software, where Poloniex is just a website that you can log into and trade.
I don't see centralized exchanges going anywhere soon.
Ease of use cuts both ways, EG when Polo is down from DDOS or too many users, or you are a user in New York State/Venezuela/Iran.
Convenience cuts both ways, EG when Polo demands to sequence a stool sample to authorize withdrawls (but not deposits of course) or when they get hacked/Goxxed.
Bitsquare only very recently got to the holy grail of a decentralized exchange.
Absent .gov crackdowns, they won't replace centralized exchanges soon(tm), but in a few years I expect to run Bitsquare on my phone (natively or possibly linked to a VPS backend like Mininero).
