I suppose it's possible, but I doubt he would go in alone. He is rich, but not wealthy enough to bankroll the club to greatness.
Plus the Agnelli family holding company who own the majority of Exor consists of many family members, each with varying percentage ownership. Although I'm sure the direct descendants of Gianni own more than those of his brothers and sisters, it still would be complicated, as some family members may not want to break away.