The 7000-8000+ apartments in the pipe line (or ones already built) might not get rented as more and more become completed. This Time article is showing that millennials are already leaving the city. Since the city (BPDA/BRA) does not share the number of bedrooms per apartment being built, I guestimate it to be housing for about 30,000 people, especially since the production line of construction approvals has no end in sight.
It will be like a reverse musical chairs; lots of seats and not enough people. And why rent in the city, when you can buy in the suburbs and build a family with equity.