FCO usually seems to have decent enough yields. Under threat must be anywhere where FR are competing (although yields to Malaga and Faro seem to have held up) and Lisbon, which always seems to be cheap. Have any tour operators put packages to the Lisbon area on sale yet? Of course, we've already lost Gatwick by EI, so that might be included.
Regarding access to Dublin Airport if money isn't a worry, train and taxi is probably the choice, especially if train times improve. But as has been noted, the ridiculous route of the 747 (it even loops round on itself near Busáras) tends to make one of the direct bus services preferable to this. I do find the train to Dublin more reliable though and would always add 30 mins to the estimated arrival time for a bus.