Difficult to bring up a situation in real life when we're talking about a fictitious country. Personally I don't think Utopian players should even be able to leave Utopia, let alone play for another country.
While this seems like an idea that will benefit small countries, it isn't. If you saw a Utopian 18yo on the transfer list with good starting skills, you'd see a frenzy over the bidding and likely an astronomical fee. Who would that be good for? Why, the Utopian team that's selling him does best out of it doesn't it? That's an unfair advantage. And based on sheer numbers it's unlikely to be a micro nation team that bought him.