I have the same opinion with you, I think the bittrex will replace the position of the poloniex since the service of the poloniex is worse and it is very hard for new coins to be listed .
oh god, i hope not!
i once was hoping bittrex becomes bigger and replace poloniex but looking back at how poloniex used to be, how good it was, how responsive and respective they were towards their users and how smooth and problem-free it used to be i regret hoping the same fate for bittrex!
of course it is different people with different service and may act very differently but it is the human nature and it happened too many times so far with so many different services that when they got big they started not-caring and becoming a crappy service just making millions daily...
They start out like that when they are small, but when they get bigger they seem to get an attitude.