I would think it will be ORK-MAD or SNN-MAD, but not a 'milkrun'. The days of a "stopover" are long gone. I just can't see that working at all. It is confirmed that Aer Lingus are going to join one world, its part of the IAG offer.
DUS could be a good route. Hopefully the IAG group and oneworld will pay Ireland more attention.