x2 re BA starting LCY-DUB. Shittyjet (Cityjet) have gone from being a relatively decent airline to being little better than Ryanair in terms of customer focus and product. Not a reliable option in my opinion.
T2 in Dublin is full (more technically pier E is full), so I can't see BA getting the space. It would be nice.
A nice BA lounge in T1 is the best we can hope for.