Your scenario suggests that he's already dropped it, but that we just don't know it yet. Either way I wouldn't be surprised. Trump is from a time when the 'N'-word was in common usage across the country. It would be in his lexicon even if it has gone dormant. Further complicating the issue is the fact that a double-standard exists whereby African Americans can refer to themselves by such epithets, but white people can't.
Of course that wouldn't stop the media from skewering him like they did Paula Dean (whose career was destroyed for something she said thirty years earlier).