Looks like Kraken is already doing that...
Kraken trading volume has been surpassing Poloniex lately

Nice

polo is nothing. they can't have the fiat gateway ever and so we can never get to buy coins from them except having some coin on your own and listed there. just like Kraken, coins listed on polo are only chosen ones but Kraken has the best ones.
The volume of okcoin is some low in this image.
And the volume of poloniex is over 20,000btc these days.
From wan.