Rushed approach
An interesting concept and of course Easy did this with GO a few years back, but there would still be a lot of redundancies in back & front office staff, management and the pension problem, could any of the players be interested?
Ryanair, very unlikely, wrong fleet and adding 6-8m pax is small beer for them
Easyjet, as you say possible, same fleet,previous form, capitalise on LGW position
Norwegian, wrong timing, fleet wouldn't be an issue with both Airbus and Max on order and would at a stroke establish them as a serious player in the UK, could they afford it?
Vueing IAG funded, so money not a problem, same fleet
Jet2, would be a huge leap and MAEL could transform their maintenance, probably too big for them management wise
The pension problem is the same for all, but that can be sorted by the owners, but the regulator will not allow a drip feed from a non UK company and will force the fund into the PPF
Turn around is of course possible, but dealing with the level of reduction reported in the press* will take serious management time and the loss of staff morale would come at a time when they are trying to improve the customer experience.
Having twice faced this situation i would not wish it on anybody and a swift easyJet takeover would be best for most of Monarch's employee's