FTTH or FTTC, depending on countries and areas, will be the key technology for operators to differentiate themselves
from competitors and win market share. Such a disruptive evolution of the access network should be supported by a
significant re-design of the higher network layers. In the present paper, the required features of these new WDM
networks are presented. Capacity and cost are the two obvious drivers. But versatility will be crucial to cope with an
uncertain context (tedious prediction of traffic, regulation and services) and with very diverse population densities.
Finally we also address how PON could benefit from mature WDM technologies to ease the global network design.