Dublin, Belfast, Southampton, Prague, Bratislava, Leeds, Cardiff ,Exeter , Durham, Budapest, Berlin, Rome, Madrid, Poznan, and now Lisbon have all been lost to Cork since 2007 and no domestic or foreign carrier has taken them up so I wouldn't hold out too much hope for Newcastle if Jet2 do withdraw.
Only for Ryanair's decision to significantly expand their Summer operations at Cork since 2010 the situation would be dire.