NCLABZ has always been a popular route and lets face it Flybe are dipping their toe in the market on this route purely because the Q400 has a gap in the thrice daily NCLLGW schedules.
With an aircraft based at NCL from the end of March and one in ABZ too, it is likely that their is alot more to come from Flybe at both of these airports. Eastern will survive on NCLABZ for the time being, however once Flybe go anymore than once daily then Eastern will suffer. It maybe be possible to sustain both carriers but Eastern will be facing an uphill struggle to retain market share on the route.