With RE now operating for EI, the ailine count is one fewer, even though noone has left/gone under!
I don't think it's the case that ORK has picked up much of the SNN traffic. Those fares were incredibly low, perhaps, capturing an section of people that would not have travelled at all at higher fares, which is what is seen these days on remaining SNN and ORK routes.
I'm not sure what the CAA can do to attract more airlines to ORK, some connectivity into FRA/BRU/ZRH would be good. We see much less variety these days, hardly surprising with 4 EI airbus 1.5 FR boeings and the pair of EI/RE ATRs. Most lucrative routes are probably covered.