nphc flight?

Is it possible that the fall off at AKA (and perhaps other NPHC sororities) is a reflection of the increased (however gradual) integration of the Panhellenic sororities? I realize that many pnms would prefer NPHC sororities for different reasons, but it seems those that have pledged Panhellenic sororities would be a lost market (so to speak) for the NPHCs. Or is there no relationship at all?