I am not sure if I have this right, but in the early 90s, Italian football allowed clubs to have five foreigners on their books and only three on the field at the same time.
I think the ship has sailed re: foreigners at Italian clubs. If they were to attempt to go wind that back, many clubs, including Inter would find it very difficult (if it were permitted by law).
I think the best way to do it is to introduce a rule that requires clubs to have four players promoted from the youth team as senior squad members, for example, a goalkeeper, a defender, a midfielder and a striker.
When you think about it, we have the likes of Kolorov, Ranocchia, Vecino, Vidal and fucking Caicedo occupying valuable squad spots because they are "experienced". but the honest truth of the matter is that they offer 5/8's of fuck all when it comes to contributing on the field. Why can't those spots be occupied by young Italian players?