A significant downturn in travel demand---for any of several reasons---could also do this, whether travel in general or to WDW specifically. Most of those would be temporary and not structural. But not all of them are. For example, if for some reason air travel became significantly and structurally more expensive, that would be a problem for WDW (in a way it would not for DLR).
I'm not sure how good of a business it is in its simplest form.
Just buying and holding DVC resale contracts for rent seems to generate roughly the same after-tax ROI as long-term averages in e.g. diversified index funds. The latter is a lot less work, and a lot lower risk, because with a DVC rental business, all your eggs are in the DVC rental demand basket.
To really make the DVC rental ecosystem work, I think one also needs a short term acquisition/disposal/rcycle strategy that gives one extra leverage. The other strategy is to focus on confirmed reservations and cherry-pick the ones that have the highest ratio of prevailing rate per point, but that's a good way to come to DVC's attention rather quickly. That's particularly true if it is anything other than a side hustle, because then you need to be able to do this at scale.