The US can close the loophole at their end in a minute, by passing Cuba-style embargo laws. They won't do it today, because US corporations are prime benefactors of that scam, but it doesn't mean they won't ever do it.
In any case, there's absolutely no indication whatsoever that the Irish will risk jeopardizing their relationship with the Empire for little Ed Snowden; in fact, the opposite is likely true (they'd love to be the ones shipping a shackled Snowden to the NSA). It's probable that this intimation was issued to Ireland exactly because it's the country less likely to protest for being openly treated as vassal. For example, it's already quite doubtful that the stunt pulled on French and Spanish authorities for Morales's plane could ever be repeated, because public opinion in those countries is now incensed. Not everyone loves to be Air Strip One.
