According to several danish news sites, Kessler will annonce his plans for the future tomorrow. The rumors say that he will continue to box, and he is aiming for the following opponents: Froch / Groves (depending on the result of their fight) GGG Ward (if he can get Andre to Copenhagen).
His last layoff, was because he lost his father last summer, and around new year he got a son. But you are right he is not that active.