United are gradually phasing out their 752 & 753 and 767. A321XLR is the reported replacement. They will have to make a decision how to retain routes or possibly drop some while the new aircraft currently on order enter service. I wouldn’t be surprised to see EDI-ORD dropped in the interim period. With EWR performing well, you’d expect them to ramp up the battle with Delta for the NYC market, particularly as they are scheduled to return to daily in November with a more premium heavy 763, offering premium select. The question is, what aircraft type they will use?