His blistering pace was his USP. It doesn't mean he's of no use to City being slighter slower, but after 8 years together, Kyle's in need of a fresh challenge & a new start for him & his young family, & City need to begin the much needed rebuild of our ageing squad.
Walker is merely the first of several legends to be leaving us over the next two seasons. This inevitable exodus will herald the next iteration of Guardiola's Manchester City. The good thing about it, is Pep seems bang up for the rebuild & the challenges ahead, which is great news for City.