With LHC coming into operation very soon an upgrade plan for the whole CERN accelerator complex has been proposed to allow full exploitation of the LHC potential in the future as well as giving increased support to traditional and possible new experiments at lower beam energies. This plan foresees replacing during the period 2011 - 2017 all the accelerators in the LHC injector chain (Linac2,Booster, PS) by new machines (Linac4, SPL and PS2) except for the last - the SPS. In this scenario the SPS should be able to reliably accelerate twice higher beam intensity than achieved so far and therefore significant improvements to the machine performance, in addition to the increased injection energy due to PS2, should be found and implemented at the same time scale. The present status of proposals and ongoing studies for all accelerator injector chain is described with main emphasis on the SPS challenges and upgrade plans
