The 5th generation of mobile networks (5G) is the next major phase of mobile telecommunications which will provide the foundation for the Networked Society. To support 5G, transport will need to cater for increasingly diverse service requirements. It will need to support emerging 5G radio systems in terms of higher capacity and increasing number of cell sites. It must also cater for increasing need for radio interference coordination between sites as well as cost effective radio access network (RAN) deployment models, and provide a flexible platform for sharing of resources where different actors through transport application programming interfaces (APIs) have access to network resources and diverse transport services. In this paper we summarize the key defining factors for 5G transport and outline a concept for programmable transport based on WDM and exploiting emerging optical devices enabled by integrated photonics.