Firstly if I am right the new legislation regarding "new" foreign rule will have to meet EU labor laws and I am pretty sure that new legislation will violate spirit of Euro, and hence will not be accepted.
It doubt whether it can be be implmented even if FIGC wants to.
Beside, I do not think limiting the number of foreigners will improve Italian team significantly. The problem of Italian team, IMO, is not that it lacks talent but it has been badly trained and organized prior to the tournament. Few Trap specialties did not help either. Good managment and a change of attitude is more needed than a rise of new star.
Beside, imposing new rule would be extremely unfair on players who are currently playing Serie A, and clear discrimination against their employment status. And lets not forget that foreign players add excitement to the league, gives Italian teams competiveness in the CL, and brings different culture and playing style to the league, which young budding talents might find it valuable.
If Italian teams are not willing to play young Italian star than it is ultimately their fault for lacking insight rather than foreign players that has been hired. Carraro should stop blaming others and look into mirror for a change.