Given the injury hit season he's had, he is owed some time before we start claiming his legs are going. Maybe they are, i can see the indications that they may be, but lets just hold off calling that and give him an actual chance to fully recuperate from a major injury that hes not been used to.
Even if they are going, it's not the end. There's a reason why he's the greatest midfielder in premier league history, he will adapt and learn not to rely on his running as much. His intelligence above anything is what sets him apart, he'll use that intelligence to alter his game and still be effective.
he's got plenty left to give yet, let's give him some time before we're writing off one of if not the best player we've ever had.