5G technology ripens and operators are preparing for commercial 5G networks roll-outs. 5G technology brings about significant architectural changes and incorporates variety of advanced technologies like CA, CoMP, massive MIMO etc. that promises a lot of benefits in terms of network capacity, spectrum efficiency, user throughput, and makes mobile networks ready to meet challenging requirements of emerging applications including IoT, M2M, V2X. In turn, these developments create new and sometimes challenging requirements to synchronization in mobile networks. The presentation explores challenges related to cost-effective provisioning of highly accurate synchronization in mobile networks, outlines a strategy based on the clustered distributed timing architecture to achieve accuracy that can meet requirements of 4G and 5G networks, and discusses applicability of the recent PRTC-B/ePRTC specifications for this architecture.