I flew PS for a lot of years. Most of the passengers flew out of JFK precisely because they would never go to EWR. Like many of UAL's decisions in the last 3 years, we will lose the majority of the PS people, and significant portion of that revenue 1st class PS will go to Delta and American.
There were almost no connections anywhere out of JFK, the entire plane's load's destination was JFK. What's more, we will lose is the PS passenger that connected to the pacific and further out of SFO and LAX.
We made huge amounts of money there and now just giving it away...again.