That would require butting heads with the Portmarnock crowd again, they might not bother if the new runway is the 3,600m they now want, only the heavies will require more than the 2,600m already available. The DAA might not consider it worth their while.
Current plans are for 3110m x 60m so not the 3600m and SNN retains longest. Suppose DUB need's to give them something to shout about
RY28 extension is 390m would be added and it would be 3,027m. Cost of 55 million and would require planning application, house buyout/insulation programme, 34/28 intersection re-profiled.
Not sure what the daa position is on this but they would of seriously considered if the cap was much higher for new one I think.