Check out this timely little video report by McGill architecture students Veronica Lalli and Theodore Oyama dealing with the demise of the Negro Community Centre, a Litte Burgundy landmark that was recently razed.
The video has some solid interviews and even contains scenes of the demolition from a few days back.
I haven't had time to watch the whole thing but the organic process of decline, dilapidation and ultimately demolition stems in part from the tax-free status of certain religions and almost-free status of associations as well as the bureaucratic hesitation to rezone from institutional to residential or commercial when need be.
Anyway, to put it in layman's terms, things fall apart. Please feel free to add your take on it in the comments section below.