What's going on with them? they were on the top of the game but no one is talking about them anymore. I also see a lot of ICOs around but honestly, I can't even remember the last I've seen a project announcing listing their coin there.
What happened to them is pretty normal it almost happened with Bittrex too ( Binance kicking them from #1 to 2# ) . When you stop working on your product that what will happen , Poloniex fault was thinking they will remain #1 without doing anymore effort which was huge mistake , Bittrex the same but they are on top of it now . When you expect to remain #1 with a lot of other exchange doing things better and cheaper than you then you are wrong . For example If Bittrex did not start work on there fees soon all user base will be based on Binance .
The new owners for Poloniex did not do anything new until this moment , hope they do soon .