Highly granular calorimeters and particle flow algorithms are essential tools for achieving an excellent jet energy resolution. This is a key asset for precision physics at future high energy particle colliders aiming at precise physics measurements. The PFA concept is best supported by a silicon tungsten electromagnetic calorimeter. The R&D as carried out by the CALICE collaboration has shown the feasibility of a fine-grained pixelization while assuring high operation stability. Our concept has been selected to compete for the upgrade of the CMS ECAL. The latest version of our detector concept, featuring 1024 channels on 4 dm2 board will be presented including technological choices for an application on an ILC. First thoughts for the CMS ECAL upgrade will be discussed.