Sounds like it's time to take a step back!
Firstly why would BE have a 'tantrum'? They are still, and will be for a good while yet, the Islands main carrier. Personally I feel a bit of competition is good for the market. BE have said before they have no interest in LCY if they did it would have happened already. LCY and LGW/LTN have existed alongside each other before and they will do again.
Secondly despite all of it's good points some people will still choose to travel through LGW and LTN.
As for prices, as the flights for LCY have been on sale for a few days there are bound to be loads of cheap seats available, BE flights have been on sale for best part of the year already so cheap seats will have gone. Also maybe it's just me but when Euromanx had no competition with BE I don't recall their prices shall we say 'low'!!