The BRA conducted a study in 1998 which demonstrated that if 8,000 housing units were developed in the Seaport (of any type) over the next few decades, the pressure index on outlying neighborhoods from the new Seaport area workforce would be relieved and employees working within the Seaport District would likely meet the supply of new housing. The full capacity of the area transit system, heavily burdened at full build, would also be relieved.
In the face of political opposition against housing at the time of that study, the BRA's Seaport Public Realm Plan lowered its sights, suggesting a goal of 5,000-8,000 housing units (2,500 north and 2,500 south of Summer Street). The BRA later quietly reduced that goal to 4,000 housing units in the Municipal Harbor Plan.
As the market for office and commercial space continues to prove more viable (i.e. profitable for development), available land for residential construction will continue to dwindle. Much of the pressure, both from the financial district and BCEC, presumes the Seaport will develop as a destination for suburban residents (e.g. office space) and tourists (hotels) with a mix of commercial amenities.
Lacking a critical mass of residents, the Seaport will be Kendall Square, lively mostly from 9-5 on weekdays. But unlike Kendall Square, the Seaport won't have the room to readapt itself to accommodate residential at a later date when people realize the properties have not attained their true potential value.
Ten years since the BRA's 1998 study, we have 3 major hotels and 3 office towers (maybe more?) completed. Fan Pier Phase One has no residential and Seaport Square Phase One is approved for predominately office and commercial space, with a scant 125 (or somewhere around there) units of residential housing. Fan Pier's 21 acres, at full build in a decade or two, is approved for a maximum of 650-675 units of housing. Seaport Square claims to have 2,500 units of housing at full build, just don't ask where the land will exist for that in the years 2020-2040.
Simply put, the Seaport is not destined to be a dense urban community of any sort. Any time the media barks about it, the BRA defensively points to a 100-unit condo being built somewhere on Broadway in Southie. And there is a rental apartment building in Fort Point going through approvals.
***** on a different topic *****
As for the proposed changes to the footprint sizes of buildings on Seaport Square, I think Shepard really said it best with reference to the A Street Highrise in that thread:
Its small footprint should be a model for Fan Pier. All of Fort Point should have been a model for Fan Pier.
Let's just hope the stumps of Fan Pier don't become a model for Fort Point.
The A Street Highrise, which reaches the FAA height limit of around 300 feet, would be a much better scale for buildings on Seaport Square than the planned megablocks, allowing for an improved street layout, alternating building types and a more interesting pedestrian environment.