Yes and No
All units will be open, but only those that have been sold to
DVC members are available for DVC members to reserve. The rest are for standard cash reservations through disney.
So, if only 25% of the BLT has been sold by 4th august, only 25% of the rooms will be availble to fulfil your waitlist, so there is still a big chance that despite the resort being 3/4 empty, you will get shut out.