As is often the case with Ryanair, I don't think Liverpool was given enough time.
While Kerry can (in theory) benefit from problems between Ryanair and Shannon/Cork airport, I see it as far from certain that these will persist in the long-term.
I also question the extent to which people from Cork/Limerick are willing to drive to Kerry to take a flight. Do they know Kerry has an airport? That the airport has flights to x cities? Who will market it... unlikely to be Ryanair...
Alicante and Faro will be interesting test cases.
Liverpool failed and yet Frankfurt persists. Liverpool was an established route from Cork and Shannon.
Aer Lingus had 1x weekly Kerry - Frankfurt/Dusseldorf (via Dublin) flights during the summer in mid to late 1990s.