In the DVC rules/regulations there is a provision called breakage. Basically, if a DVC room has not been reserved on points within 60 days, that room can and is made available for a cash reservation. My guess is there have been a lot of DVC point cancellations and since we can go out as far as August 7 at this point (60 days from today), that gives Disney a whole lot of DVC inventory to play with.
There are also points that are owned by DVD (Disney Vacation Development), either as part of the 2% inventory they always maintain, undeclared rooms at Riviera, and points recently acquired through right of first refusal (which is probably minimal since Disney doesn't seem to be exercising that much right now).
So in a nutshell there are very strict rules on what DVC inventory can be sold as cash rooms but given the current situation they likely have quite a bit due to cancellations for the next 60 days.