They already have to do this to block gen 7 pokemon, forms, attacks & abilities from going to gen 6 though.
Not really. The filter just looks for an specific number in the Pokemons ID, say "07SM". And then blocks it from going to games that don't recognize it. If I had to guess, once a Pokemon goes to SM, it substitute the gen 6 code for the gen 7. That's my bet at least.