Vilanova was forced to leave his position as manager in the summer after suffering a second relapse of throat cancer, which he continues to receive treatment for.
However, Rosell has confirmed that Vilanova will be welcomed back in some capacity when he eventually recovers from his illness.
"His illness has been the worst thing that has happened since I arrived at the club," Rosell told El Larguero.
"He is lively and strong. If he recovers, he will certainly return to Barca. I do not know in what capacity, but he will return."
Gerardo Martino took over from Vilanova in the summer.