Aer Lingus won't be pulling aircraft out of Belfast any time soon. However, I wouldn't expect to see any expansion there either.
I think there are two new A320s coming next year and Cork must be in with a fair shout of one. Fares to Amsterdam in particular have been through the roof all year and yet almost every aircraft is full in the summer and even in Winter loads are 80%+. They could easily allocate another aircraft to Cork and just have it doing extra rotations on some of the existing routes.