Cork has its own natural catchment area, and is somewhat immune to the west coast over supply of airports.
FR, to their credit (and I don't often stand up for them), tried many many routes from shannon. I can't see that large an expansion, with the exception of some UK routes, at the expense of Aer Arann - maybe BVA. However, SNN has to do this with the long term viability in mind.
If Clare CoCo run shannon - who knows what will happen - in politics anything could happen.