Recent progress of optical technology will soon lead to a variety of innovative products available on the market for designing optical networks. These products will make it possible to realize network layer functionality, such as transmission, multiplexing, routing and performance assessment directly in the optical layer. One of the reasons behind this evolution is the potential cost reduction of the overall system obtained by introducing an optical layer, over the extant transmission network, supporting the growing demand for broadband services. The paper analyses the cost reduction achievable by this emerging technology in a regional network with about two million users. The analysis is carried out taking into account a number of relevant factors, including the total fiber length, the number of wavelengths per fiber, the transmission rates, the line terminals, the structure of the nodes, considering both the optical and the electrical components, that are necessary to support the traffic scenarios expected over the next five years and beyond.