Aer Lingus Regional is the obvious brand for the route, it's worth remembering that connections would (or certianly could) also be possible onto the rest of the EIR and Aer Lingus networks, as well as any interline connections.
I think ORK-DUB is less attractive than it once was, competition from road and rail, for one. Changed economic times, too. The revenue potential at RE has changed quite a bit as well, RE now have access to much busier routes out of DUB and no longer compete with EI. EI and RE together are stronger against FR. Essentially DUUB-ORK is lower on the priority list than it would have been before.