my wife and daughter go up there before christmas every year to hit the sales. Usually it is not crowded at that time of year, and there are great deals. This LAST christmas, they said "never again". half of the stores were closed, the whole place looked like it was going out of business. Not much stock in the stores too..
The outlet stores do good because of KTP. Not the other way around. Those outlets are nothing special, their prices are not that great and most of the time you are lucky to find more than 4 people shopping in one store.
other mall outlets have opened up, and that is driving the NYC crowd there instead, especially closer to NYC or in tax free NH.
If KTP moves, Kittery rte 1 will look like one gigantic abandoned strip mall.