To me, the crux of the matter has always been population. Boston simply needs more residents and if you ever expect Fan Pier to be a vibrant neighborhood you can't expect it to be done on the shoulders of luxury residental, hotel and office space. All of which seem to be greatly overextended at the present moment.
If the entirety of Fallon's plan is ever built; we can expect a part of the city that does not resemble 'traditional Boston'. It's going to be nice but sparse and sleepy and probably still disconnected from downtown.
Charles River Park has these characteristics but it works because it's in the middle of the city and has a niche market as it serves as home for the MGH docs, foreign transplants, urban old folks, professors etc etc. It's a nice little oasis within the city and is still going strong after 45+ years.
The CRP model is obviously no longer practical though. Boston, today, must shed it's reputation for being an expensive cost of living city. It's essential that we draw in 100,00-250,000 more people in the coming years and what is required is to build volume, not quality.
Boston does of course work at 500,000-600,000 population but growth will be limited if that number persists in tandem with the current high dollar rents.
After all, if you can't fully occupy a new development at the same time you have a fairly stagant rate of population increase; something is wrong.