The whole dynamic really does continue to shift over time. And in another 15 years or so, the dynamic will start to shift even more with the leases on the oldest properties start to become very short. Will people pay $100 a point for BCV when they only have 10 years left? Unlikely. With BCV and BWV both being up in 2042, will that swing most resale buyers on those properties to Riveria - being potentially the only "Epcot" resort with an extended shelf-life? Or will people favor the shorter/cheaper commitment available?
And how will Disney handle lease 'renewal'? They tried an extension at OKW, and it didn't go over very well, but that might have been because there was still so much time left on the contracts. (My suspicion is when these contracts get down to around 10 years left - Disney will try again to offer extensions like they did at OKW. Maybe similar to the 15 year extension, but could also see it being somewhat longer (20-25 years). Depending on the price - this could also "goose" the resale market. (If a 20 year extension is price significantly lower than a "new" resort, it may be seen as favorable, especially if it brings re-sale owners under the "direct" banner.
Of course, that's a ways away.