Miami isn't the worst idea in the world. It would generate a certain amount of tourist traffic and is an important hub for services on to Latin America.
Where some potential seems to open up is smaller airports that have no Customs or Immigration facilities. Preprocessing in Dublin could make it the only European airport thy could offer. But... That would be heavily contingent on a change in the business plan on European routes. They would have to provide higher frequency in smaller aircraft than is currently offered I'd Dublin were to be a transit hub. Easier said than done with Ryanair around.