That's gonna be a disaster.
Players playing for countries they have not been born in or have no meaningful relations to or because they just about qualify for a citizenship and bribery and corruption like the one that saw Qatar win the right to host the 2022 WC are two of the things that are eventually lead to the demise of international football. It's become almost as commercial as club football itself. And if the two products are too similar, club football will always win that battle.
I think players should declare which country they will play for (the ones said player eligible for, of course) as soon as he signs his first professional contract. And senior caps such as friendlies should not be discarded either.