While DVC is a timeshare, it has a very large moat called WDW that makes it different from all other timeshares out there. As long as people want to stay on site at WDW then DVC or a Disney hotel is the only option. So there is a limited supply of onsite accomodations and a lot of demand, as long as that doesn't change I don't think the value of owning DVC will change.
I agree. I think Disney timeshare is unique in that there is little substitution. The same analysis that I did on Disney doesn't really apply to other timeshares. If you try to rent out your Marriott time share for prices that are too high, people will just go somewhere else. For Disney, there is really no alternative if you want to stay on site. As long as there is a sufficient spread between Disney hotel rack rates and DVC rental points, I think the value of DVC rental points can be maintained.