Consumer bandwidth is showing no signs of slowing down and operators are now forced to explore access network migration strategies that will satisfy the anticipated bandwidth demands for the next decade. However, evolving today's access networks towards NG-OA architectures will require a multi-billion euro investment. Consequently, an important strategic aspect is the need for a thorough techno-economic analysis underpinning the development of NG-OA architectures that feature a minimised total cost of ownership (TCO). New approaches and methodologies to analyse TCO will therefore be required to provide the necessary business case data underlying the multiple commercial opportunities arising from such a regulated, yet competitive market environment. Network energy efficiency issues are also becoming an increasingly crucial aspect due to economic and environmental pressures. The evolution towards an"open access network" environment in which multiple market players will have to cooperate at various levels will require reliable, "zero-touch", automated management and open interfacing, clear service definitions and low operational complexity. The use of optical technologies as well as network consolidation (reduction of sites and active nodes) to reduce network costs will have to be consistent with the open access network model.Focused on European requirements, OASE (Optical Access Seamless Evolution) will addres these challenges to develop an optimised multi-terabit NG-OA architecture that will span at least 100km and serve Gbit/s services to a minimum of 1000 customers.In contrast to other approaches, OASE will be unique in developing the future NG-OA architecturefrom a multi-faceted perspective. This shall not only include the technology point of view, but alsoencompass the economic, regulatory, environmental and complex business models associated with such open access network architectures.