The big question is what is the purpose of international sport. Really it is meant to be a contest between the best players from different nations, and traditionally it has been the highest honour a player could aim for - to represent their country at the international level.
We live in a global world where people have been migrating between countries for generations now so lots of people have mixed heritage and there is always going to be some flexibility in eligibility criteria. People generally identify with somewhere. So you get Iestyn Harris, born and bred in Oldham, with a Welsh name and Welsh rugby supporting family, he obviously identifies with Wales as a rugby player so he was always going to play for them rather than England. Gareth Widdop and Bobby Fulton were both born in England but spent most of their lives in Australia, one identified with England and one with Australia, that's fair enough.
Where international sport loses credibility is when fans start to sense that it's more an issue of convenience where players exploit loopholes in eligibility to get international caps. It loses something in two situations: either when a player really identifies with one country, but realises they are unlikely to get picked, so they "trade down" to another country to get some caps, or when a player identifies with one country but "trades up" because they realise they can play for a better team. I have more sympathy with the second one, because there are some cases where a player is really good enough to be a top international and the international game doesn't offer him very good opportunities if he plays for the country he identifies with - eg Eoin Morgan in cricket, or a lot of the Pacific Islanders in rugby league.
The first one grates with people more because it seems like it's just about convenience. I doubt Blake Austin identifies himself as English, if he thought the Kangaroos would pick him, he wouldn't declare for England. Same with Rangi Chase and the Kiwis. Yes, nobody is breaking any rules but it does damage credibility when people think they are exploiting the eligibility requirements. I'm sure England RU fans thought the same when Henry Paul and Vainikolo turned up in England jerseys.
In RL you have the additional problem of a lot more swapping and changing of nations which just shows that the game is trying to manufacture an international game out of a limited pool of players. When the World Cup comes round you read the match programmes and it will say stuff like so and so won 6 caps for Tonga, then he won 13 caps for the Kiwis, and is now back representing Tonga for this world cup, and is playing against the Kiwis....it isn't the spirit of what international sport is supposed to be about.
I doubt Blake will be realising a lifelong dream when he pulls on an England jersey, or describe it later on as the proudest moment of his career, like an international call up normally would be (or like it would be if he'd played for the Kangaroos). But he will get a cap and can say he's played internationals and it will be another experience he can talk about from his time in England I guess.
