This is going to affect the exchanges that use tether - Bitfinex, Bittrex and Poloniex.
But the big Korean exchanges will be unaffected as they mainly trade against the won. Ditto with the big American exchanges that trade against the dollar (Gemini, GDAX, etc)
Bittrex already announced the introduction of USD trading pairs. So I guess they are getting ready to ditch USDT if necessary