I can see the possibilities of billboards etc. One such enterprise has already failed with a business plan targeting billboards-Berliner. Who would pay for infrastructure on and around the billboards needed to support the antennae? Surely there is more to utilizing billboards than just plopping an antenna array on them. These preparatory costs must be borne by someone. Who will pay these costs when many towers are ready NOW to be colocated on in many cases?