The implementation of Multicasting (it's in GNUnet roadmap) can quickly make the mesh more efficient. In cities, wifi devices can start working together and manage bandwidth in a better way. Then a program can signal that, for example, 4 different wifis with GNUnet cover the same physical location. Somebody (network analyst hobbyist) could write to them and offer them to get a communal wifi that uses GNUnet superior performance while saving a lot on ISP services.