Heres a report on AirWise News:
Aer Lingus Eyes Consolidation Via Stake Sale
I know Bloomberg were reporting Aer Lingus was stepping up negotiations with OneWorld, but I really can't see them rejoining the OW alliance. Christoph Mueller has a clear vision not just for Aer Lingus, but for Dublin, and that doesn't tie in with what BA have in mind, which is to continue Aer Lingus as a feeder airline into Heathrow.
For Aer Lingus to turn Dublin into a significant connecting hub, they can only do this in Star Alliance or SkyTeam. The last thing BA want is for them to lose connecting traffic from Ireland, which accounts for around 10% of their total long-haul revenue, although maybe this might force to make Aer Lingus a serious offer?
And then theres the fact that in recent months we've seen Aer Lingus step up links with Star Alliance carriers with the new codeshare agreement with Spanair, and the announcement that they're expanding on their Joint Venture with United Airlines. The fact that the timings into Star Alliance hubs have also been changed for the Winter schedules to allow better connections is also an indication that Aer Lingus is leading towards Star Alliance.
So I'm not ruling OneWorld out, but my moneys on Star Alliance.