There's already a scheduled 23:55 AGP-DUB, so they are more than willing to operate that late. However, that is the return working of a 19:15 DUB-AGP, so it doesn't allow for the Shannon timings.
I was also surprised that Nice was cut entirely. Not sure it was ever daily, but it was year-round with reasonable usage for ski traffic to Méribel, La Plagne, Les Arcs, Alpe d'Huez etc.
However, so many destinations in Cork run into the problem of being viable when the route incentives are in place, but when those expire, an airline can use the same aircraft more profitably on a different route with full incentives. The design of the current scheme doesn't really encourage stability. It's why we see routes like Nice and Lisbon back after a hiatus and why I'd thought it might be time for Rome's return.