It's almost like how some cities in the eastern half of the continent call themselves "post-industrial", are we becoming "post-office"? (applause please)
I don't know what the costs are to keep an empty building, but it seems extremely wasteful to blow something up when there might be start-ups and other groups who need space but can't compete with big O&G. I expect multifamily residential demand will stay relatively high with demographics what they are these days (later starts, smaller families, more living alone, work/life balance, etc). I suspect there may be issues with office towers being wider than residential towers and having a core of unusable space towards the centre of the building, but maybe that would be a good place for storage, gym, laundry, etc.
Let me know when I can get 1000sqft with a kitchen and a bathroom for $2000/mo in the Bow!