Sounds like a great economic opportunity for some construction contracting companies to specialize in these offices-to-apartments conversions. It is possible to gut a lot of the "soft" walls and infrastructure on each floor, bring in more plumbing, and re-build a new floorplan. I'd wager the companies doing these conversions can make a tidy profit (and create employment opportunities!), and still charge the building owners a reasonable-enough rate that they'd rather go this route than sell a dying office building at a huge loss.

You can get a bit creative with this too: e.g. dedicate some floors of the new apartment skyscraper as co-working spaces, and try to plan it so that everyone who rents in the building can use the co-working spaces for "free" as part of their rent and still have some leftover capacity to sell co-working memberships to others nearby as well.