They are already doing it -
Man City U18 squad:
Spain DF Pablo Becerra
Switzerland MF Daniel Lema Traba
France MF Thierry Ambrose
Portugal MF Wato Kuate
Spain MF Angelino
Spain MF Manu Garcia
Republic of Kosovo FW Bersant Celina
Chelsea:
Sweden DF Ali Suljić
Ivory Coast MF Victorien Angban...
Personally I think the bigger issue is the big clubs filling up their youth team with foreign players and limiting the opportunities for British players. The regulations above wouldn't stop this from happening.