Offices have become the weakest link in commercial real estate, and the sector’s distress is rippling out from individual investors to the economy at large. But Arlington, Virginia, isn’t going to let 9 million square feet of prime real estate collect dust. The otherwise thriving, mixed-use suburb of Washington, D.C., is enacting zoning changes that will allow vacant offices to be occupied by breweries, makerspaces, arcades, laboratories, vertical farms and more.