BFS - ORK is particularly interesting because of the vast amount of cross-border business across Ireland. Driving Cork - Belfast is a full day's work, and it's still a good five - six hours by train, including connections etc.
RE can't really increase their ORK frequencies from BHD, but they could strengthen their position with some imaginative runs to other airports in the south that are more than five hours drive from Belfast - KIR, SNN perhaps?
*j*