It was just a joke I think.
Is Magnus Carlsen retiring
And it was at this point that modipaduollemmers dropped the question, as there was nothing left to be done.

I'm getting a premonition that he might retire if he loses a world title match. He's got plenty of money and he's accomplished so much, there's nothing left to prove and nothing left to motivate him. Except maybe trying for 2900 but I'm thinking there aren't enough players far enough past the 2800 level to make that a realistic goal.
Is magnus carlsen really retiring or is it an april fools joke?