Faster trains is all very well but you still have to travel onwards to the airport. And now we've AirCoach and GoBe doing Cork to Dublin Airport in 3hrs 30 with only one stop.
And thats why Aircoach and Gobus are running lots of half empty buses, give both a few months and they will scale back there operations and BTW 25 minutes from city centre to airport during rush hour in Dublin..need I say any more. Currently the quickest train from Cork takes 2h30m that will drop to 2h and other services from Cork take 2h45m-3h that will drop to 2h15-20m through better scheduling and line speed increase which Kerry and Limerick services will benefit from. Frankfurt EI is only option becasue LH are only operating there mainline services from FRA and MUC from 2013 (I assume there regional jets are also gone from FRA) and they would want a daily service at least. Swiss to Zurich would be another godd option, good onword connections from Zurich. They would have small aircraft that would be ideal. Would expect lots of seats to be booked by tour operators which woudl help it.