It looks like a good move, to increase the exchange trading volume. If all security stuff was done the right way, the most crypto pairs an exchange has, more people it will attract. It is a good deal for both sides, even best if it conflagrate a "fee war" between the exchanges (from my "user" side of view
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You made some good points there, both from an user point of view and an exchange point of view it really is a good deal.
A significant shift of Dash trading from Poloniex towards Kraken, would also be really nice. Time will tell i guess....
So we have Bitfinex, Kraken .. who will be next ?
Personally i hope GDAX will add Dash someday, i hear it has lots of trading with much higher limits for traders then for example Coinbase (which GDAX has a connection with).