I have thought about this a lot, as in probably 3 or 4 years we think we'd want to buy
DVC on the west coast.
I think that once DHV (?) makes it all the way to the resale market, it would have to adversely impact resale prices for VGC at least a little, as DHV will almost certainly sell at a lower new and resale price vs Grand Californian (as Grand Californian is their premier hotel).
One consideration that will probably help keep VGC prices higher though is that any contract purchased resale will likely only be good at one or the other, even at 7 months. So to a west coast buyer, VGC will continue to live in it's own little bubble.