This exactly why NI needs devolved power to set it own aviation tax, sorry to keep banging on about APD, but it is hurting our economy, it's that simple!
The only way either airport could increase it passenger numbers would be to offer a subsidy to FR but that would now be far from easy, at BHD the runway length issue and now the seat cap would need to be resolved and at BFS it would be a huge risk in terms of what LS & Easy might do.
Short term loss of profitability at either airport is not of major concern provide it's short term and yes starting over you would only have one airport and neither site is ideal