I don't see this as likely. But, we are both guessing. Either way, DVC is not the only system that is seeing availability tighten over the past few years, so there is something macroscopic going on.
Realistic macroscopic factors likely to have a larger effect than the economy in a fixed point use em or loose em timeshare system:
1. Increase in renters, ease in rental process, and increase in renter knowledge requesting rooms earlier.
2. Increase in owner knowledge - as you get locked out of the room you want, you book earlier
3. Increase in walking
4. More owners with a small number of points for the purpose of booking studios decreasing studio availability (one bedrooms are still not a problem).
5. More owners across more resorts increasing competition at in demand small resorts resorts (SSR studios aren't a problem most of the year seven months out. Nor are VAKL studios)
6. Studios moving from sleeping four to five which increases the demand for studios.
7. DVC lowering the point buy in minimum - increasing the demand for studios.
All those are going to have much bigger effects than the idea that a significantly larger number - a number that makes it noticeable to average bookings - get used and not wasted in an up economy and that Disney does no adjusting for a noticeable variation in their cash bookings.
Finally, I have perceived in increase in the postings of "there is nothing four months out" that has other DISers checking and saying "what are you talking about, there is plenty four months out." As more rooms are added to the system, there are fewer rooms proportionally at VGF - and VGF is going to be harder and harder to book seven months out. For those people who perceive "nothing" is available when there are studios out at SSR or VAKL or OKW and one bedrooms at other resorts - yeah, availability is tightening, and that has nothing to do with the economy - other than DVC continues to sell points and the more non home resort points are trying for those few VGF rooms, the harder they are to get.