Considering that Atlus did jacksquat to change anything in Catherine they're certainly not going to remove shit in Persona 5. The only things that could change are some removal and date changes for events since they're adding in multiple new confidants and added more active months to the in game time. By the time you got Haru added to your party it was close to the end of the game(even if you did every sub event thus far). The Royal will stretch it out more so it's not as rushed.
IIRC P3P did condense some of the character events so while it may have taken two in game days to trigger the end point to an event and raise your social status with that person, they condensed multiple events that would have taken multiple in game days in the original game down to one single event day. At most I figure that's what going to happen with P5's events that are in the base game in order to make room for the newer stuff. Futaba's mom is visible in the trailer which means the third Dungeon's post events are definitely not going to be the same.
