I don't want to reopen this 'blockbusting' quarrel, but I think the word being looked for is closer to 'megastructure'.
Blockbusting, correctly noted, was a process seen during the urban renewal schemes of the '50's and '60's where banks had marked areas as undesireable due to their own internal calculations - race being a factor in those - and vast areas were levelled accordingly due to the inability to get credit for new structures, leaving it wide open for government agencies to provide the capital and means. This is not the same thing as regular city planning and bartering, new development on a block or wholesale 'urban renewal'.
What the Gehry structure does verge on, however, is being a megastructure - the kind loved by futuristically-minded '70's architects, particularly. Though I don't think it's a megastructure so much as simply a very large one. The closest Toronto has ever come to having a megastructure would be the incomplete Metro Centre plan. After that, we see 'children of megastructures' around the city in The Eaton Centre and, arguably, York University.
I think Sp!re's protesting about a very, very large building on what was is now a much more fine-grained historical area. That's not appropriate for the received historical use of the term 'blockbusting', but is closer to 'megastructure', even if it isn't, quite. So we might have to make due with 'Very, very large building'.