Only problem I can see is regulation in their future, which is already something which is hurting them right now. You can see that back in the day Bittrex didn't have to go through any sort of AML/KYC regulations, now they're being forced to do it (and complying) due to the amount of money which they have running through their systems. I'm expecting more regulation to hit them soon due to them being #1 in the exchange marketplace.
Bittrex don't trade fiat so where is the AML/KYC required?
Bittrex are not number #1 in the marketplace, they are like #14
https://coinmarketcap.com/currencies/bitcoin/#marketsI think he was talking about altcoin exchanges. Bittrex was definitely the highest volume altcoin exchange after taking so much of Poloniex's traffic. But now with all the KYC and account locking drama, some of that volume appears to be leaving for Binance, HitBTC and Cryptopia.
The fact that Bittrex voluntarily registered with FINCEN suggests they are a money transmitter already, which subjects them to AML/KYC requirements. Also,
they do accept USD wire transfers from customers:
Bittrex allows for the purchase of USDT in the amount of $100,000 USD or greater via wire transfer. The wire transfer process requires that your Bittrex account is Enhanced Verified, and you provide us all the necessary information on the wire transaction in order to process it.
Wires are processed using $1 for 1 USDT (Tether).
The Tether markets are also a legally murky thing. By definition, they are a derivative instrument, so I'm not sure how that affects things. I'm not convinced that, for legal purposes, they are the same as a POW coin like Bitcoin or Litecoin.