In football terms, Mexico is part of CONCACAF, which embraces North America, Central America, the Caribbean, and 3 countries from the South American Mainland (Guyana, Surinam, and French Guiana, which, more properly, may be a Department of France).
CONCAAF's Gold Cup competition has its finals every 2 years, and I don't think that Mexico, the USA, and Canada, ie the teams categorised as North American, have to pre-qualify.
These teams seem to be automatic finalists.
So, if we sign Mexican internationalists, they will be likely to disappear every 2 years, much like African Internationalists would.
To have work permits renewed will they have to maintain their Internationalist status? I am unsure.