When will Roger Federer retire from professional tennis?

Roger Federer, aka G.O.A.T, is the man who defines tennis. He is not young anymore (born in 1981), but he still has golden hand when holding his Wilson Pro Staff tennis racket.

The question about his farewell to professional tennis is present for the last five years. The moment when injuries start to take its toll already happened. How long will we see Mr. Federer on ATP courts?

When will Roger Federer retire?