This really depends on the specific building. There are many office buildings that could have slapdash remodels done to make them habitable and revenue positive, and there is plentiful pent up demand for affordable rents in urban cores.
Nevermind the knock on effects of retaining and growing the on street retail base that has fled entirely commercial sections of many urban cores. You don't get a safe, friendly neighborhood when the streets are deserted every evening after 5:30pm.
As cited elsewhere on this thread, it really only works for old buildings and not for huge swathes of the newer-built commercial real estate that’s sitting empty right now:
Again, we also have to think about what the incentives would be for preserving the value of the general case of the asset class, not whether individual buildings are convertible.
Generalizing the forest while ignoring large swathes of what it consists of is a bad idea, not every metro area has the same building makeup and composition as NYC.
NYC already has seen many extreme building conversions, for example turning large apartments into micro-apartments. Many other cities have not had the economic pressure for conversions to occur.
When these buildings default and their property taxes go unpaid, the locality will have to do something with these properties, and often the financing available to municipalities is much better than what the general market can get.
Nevermind the knock on effects of retaining and growing the on street retail base that has fled entirely commercial sections of many urban cores. You don't get a safe, friendly neighborhood when the streets are deserted every evening after 5:30pm.