The CO BRS-EWR reaches its fourth anniversary next week (daily March-October and 5 x weekly November-February).
For much of the time the loads have been reasonably good, some months excellent (CAA stats), but for the most part not quite as good as the other UK regional airports on this route.
However, it is rumoured the airline struck a good deal (for them) with the airport so it would seem they have been happy to have kept it running for four years.
It's not rocket science to suggest the current economic turmoil will be a major test of its sustainability.
BRS and LBA share many similarities and as LBA has MAN, BRS has LHR, a much bigger airport with many more options than MAN, so perhaps in that repect LBA might be better placed than BRS because LHR does see a lot of transatlantic travellers from the Bristol area who, for varying reasons, don't use their local CO service.