Now they're separated by a commercial data link. When that link breaks ATC breaks, this is because they literally moved the staff from EWR to PHL, so you can't even revert when this occurs. This is why NATCA opposes and opposed the move.
It's even a little worse since this type of failure had occurred before and some of the controllers who experienced it took leaves from their positions reducing staff availability even more. It was an absurd change that set of a chain reaction of consequences for the system as a whole.