The problem here is zoning laws, in most places in the US you can't build businesses right next to residential. We would have to change our zoning laws and do something similar to a 5 by 1 (bottom floor is retail, top floors are residential)
The 'zoning' here is more building by building rather than neighborhood based.
But I mean the same kind of administrative issue holds back conversions here. Most Office buildings here would be ideal. They're not that big because here it's illegal to offer office space without plenty of daylight.