The reason VGF is so booked is that it is a new resort and everyone wants to give it a try.
In a year or two, the novelty will wear off and people will want to stay at the NEW Poly
DVC and availability for VGF will open up more. Of course the selling point will be that people will need to BUY at the Poly to book a room there (they always say that).
The #1 problem with VGF is that the point cost per night is VERY high as compared to other resorts and people will eventually gravitate to less expensive rooms to use their points.