Anand usually isn't the world's number one even if champion. He seems to be good at winning events sometimes with judicious use of draws and critical wins (Giri has the draw part yet not the critical wins). Probably he won't be able to beat Carlsen or Wei Ye eventually, yet he could make the candidates in the future.
There is no point in Anand retiring; Karpov didn't. Instead he should see how long he can remain a super GM...maybe into his late 60s, and make money advertising health supplements for keeping older brains sharp. Retiring to Valhalla (it's a retirement community in the east) or Pittsburg probably isn't such a wonderful thing. Intellectuals should increase productivity until shortly before death, while athletes tend to need to retire early (maybe 40) and collect a pension.
Of course some male marathoners compete until 80 I think, while women quit a decade sooner.
