I too can't see Jet2 being at all interested in Gibraltar, nor any of the other major operators (Thomson, Thomas Cook...). Flybe could potentially be a good match?
In the short term, all we can hope for is more Manchester flights with easyJet - there is certainly demand as most of their flights for this month are sold out or being sold at extortionate rates.
I've chosen to double the journey time and go with BA via LHR - cheaper, better product and at least I can build up tier points to work towards getting some of the perks I was accustomed too with Monarch's Vantage Club.
In terms of BA from LGW - they should look at Monarch for a reason why to not bother. They tried muscling in on Sleazy's territory (I heard in response to EZY starting MAN-GIB) with similarly timed flights from Gatwick and having flown with MON a few times, the flights were barely half full.
Plus how many more London flights does GIB need
2 or 3 a day and the North is now served by only 2-3 flights a week!