It's implicit that an increase in inbound tourism numbers is expected if the tax is to stay at 0 (Everything I've seen suggests it has been reduced to 0, but not abolished; this would make it easy to resurrect if desired). The focus is very much on increasing the number of visitors, not improving business connectivity and certainly not sending Irish people out of the country on holiday.
I would have thought for Knock, UK routes offer the most potential, but FR could also consider Beauvais (although it would need to operate as a W), Eindhoven, Charleroi and may risk a return to Germany.