It's bad news really if you ignore the spin.
DG was always going to be OK. He declared in 2003 before the rule change. To apply rules retrospectively would open a huge can of worms and rule many players ineligible for their national teams. NI would lose Maik Taylor for example.
It does appear we've lost the case. FIFA haven't made an announcement yet but that is the clear interpretation.
The FAI can appeal. Whether they will or not is another matter. They probably have other things on their mind at the moment.