I guess that leads to the question, "What happens when there is nothing left to build?"
From a land perspective, it's doubtful that will ever be an issue. DVD only needs to fill about 25 years with newer properties before ownership of the first wave of resorts begins to revert back.
Eventually, even if they can build more resorts, they are going to start running out of interested parties to buy them. Demand isn't unlimited and they would have to be a lot closer to market saturation now then they were, say 5 or 10 years ago.
This is the other issue, and it's manageable to a certain extent.
First, remember there are new families discovering the Disney parks every year. My kids are 12 and 9 now. In another 15-20 years, they may be starting families and purchasing points of their own.
IMO there's no reason to believe the market will ever be completely saturated.
The other issue involves profit margins. Every time
DVC raises prices, they alienate a certain portion of the market. The pool of prospects grows smaller. However, with higher prices they also stand to make more on each sale.
For the sake of argument, let's assume that at $100 per point, DVC is making $50 in profit while the other $50 goes to cover construction and marketing expenses.
Raise the price to $150 per point and with the same $50 cost of doing business, they are pocketing $100 in profits. Essentially sales VOLUME could fall by half and they will still make just as much money.
In my opinion, this is exactly the formula DVC is following right now. Rather than making DVC affordable to a vast market, they are building smaller properties with much higher prices than we saw 4-5 years ago. The smaller properties lower Disney financial exposure in times of economic crisis (back in '08-09 they had no fewer than FIVE resorts under construction simultaneously when the economy crashed) and it reduces the impact of resales on the specific resort being marketed. Chances are VGF will be totally sold out in about 2-2.5 years before its contracts begin hitting resale sites in any volume.
Could they eventually run out of buyers? Perhaps. But all things being equal (economy) it's a market that will continue to grow as new families discover the Disney parks for the first time.
Plus, unless you add on to existing DVC properties, your options other than a freestanding DVC resort are limited to the Poly and squeezing something next to the Yacht Club, unless they were to go the "Moderate" route.
Off the top of my head, VGF, Poly, Ft. Wilderness, second Contemporary Tower and at least one stand-alone resort are in the mix at WDW. That's at least 15 years worth of sales right there. Something at YC or more BC units are a realistic possibility, too.
Disneyland Hotel at DL will eventually happen. And Aulani is going to be selling for years to come.
They just need to get through to 2041-ish when BoardWalk, Beach Club, Wilderness Lodge and others can be sold all over again.