The LCY-DUB route is not bookable after 31 May so its termination seems to be correct
I suspect all 3 carriers on DUB LCY are losing a fortune. Fares are very attractive and an educated guess would be that yields are too low. Passenger numbers have sky rocketted on the route.
For CityJet's sake Flybe's exit (if true) would be timely.
The only difference between DUB and other LCY routes where BE & BAC compete is the presence of an incumbent/other carrier. BA will be in this for the long run, I can see BE facing pressures on the other routes especially EDI and those where BA has stuck it out to see Cityjet off. BE will find the same experience.
I don't that BE will be treated any differently to Cityjet.
Based on the performance of BE on BHD LCY (which is popular), there is no reason why BA would not launch BHD LCY...