I find this a rather strange event in UK aviation history, i can recall nothing like it and it must be very worrying for Monarch employees.
The CAA are many things, but they are normally very measured in the actions they take unless there is a direct and immediate safety threat, that is unlikely to be the case here.
Grey bull are no doubt used to brinkmanship, its the nature of their business in dealing/buying distressed assets, but they have been around long enough and in this industry long enough to know that with out the appropriate licences to operate in a heavily regulated industry, then their assets can quickly be sized to pay debts.
As to Monarch itself, the people i know that work there say its still closer to a legacy airline than say Ryanair or easyJet in terms of its efficiency or cost base, but a long way from the halcyon days of yore, we know that when Greybull acquired them that they were incredibly lucky with their timing, Monarch i'm told did not have the financial assets to secure forward hedging on fuel and when the fuel price collapsed they got an immediate advantage over hedged rivals.
Talk of a Jet2 buyout is in my view very unlikely, they were closely involved with bmibaby in its dying throes and watched it die then pick up many of the routes and crew without paying for any risky investment, why would they see Monarch differently? plus they have just taken on a huge gamble with expanding at both BHX and STN i doubt they have the stomach or money to take Monarch, same probably applies to Norwegian and easyJet who have not had a good year, it would be petty cash money for FR but not their style either, anyone from outside the EU will have ownership issues.
So its probably down to Greybull to find the money or another investor, good luck to all