My impression, as an outside observer (I don't fly transcons, seeing as how I live in the middle of the country), is that UA seems to be deemphasizing "ps" branding, and just offering lie-flat J with some international standards for on-board service up front.
Moving from JFK to EWR was part of that (and I realize there were competitive / financial considerations for making the move). When the remaining ex-UA 752s retire, I'd be surprised if they are replaced by a domestic narrowbody with lie-flats. Either they will use more of the HD 777s, or. If they do get new narrowbodies, they will probably be something like the A321LR for use similar to the ex-CO 752s (short TATL, plus EWR-west coast transcons).