I think that selling for BWV owners (and I'm one) involves doing the math on renting it. I could sell it today. Or I could make $8 a year or more in profit for the next eighteen years. So points are (ignoring time value of money, my effort, renting risk, the taxes I suspect few bother to pay, etc) worth around $150 to me.
I also suspect that people who have bought and held
DVC for this long don't tend to need the cash - in our case, we bought 20 years ago. The kids are through college, we are in our good pre-retirement years, and are well positioned for retirement - and the cash flow during retirement might be nicer than the one time influx. We just don't have anything we need to/want to spend five figures in cash on that we don't have other sources of five figures in cash.
Of course, each year this math will change - fewer years, higher dues - but possibly higher rental rates. And BWV will likely continue to be a "good renter" - especially if I'm willing to make spec reservations over F&W. But as long as renting out my points is more profitable long term than selling them, I don't see BWV owners selling unless they need the cash in hand. So I don't see it as "falling off a cliff" as much as "slowly decreasing in value" - and eventually, it just won't be worth the bother to buy resorts ready to expire - and your only choice as an owner will be use your point, lose your points, or rent them.
The same math works for BCV owners and frankly will apply as each resort ages - if you can rent for more than the value of the points - why sell unless you want the cash in hand, or don't want the bother of renting.