With the exception of local news and weather, there is no need for local affiliates. Local advertising can be inserted at predetermined breaks in the programming much like the cable companies do now. The days of each rinky dink geographical area having some half-assed local farm report and such hopefully will be coming to an end(which come to think about it is why the HD deadline keeps getting pushed back as these hole-in-the-wall affiliates don't have the money much less the inclination to invest the money needed for digital broadcasts).