If they are sold I really hope they are kept in operation, I'd love to see the Dart Group buy them and operate them as a southern subsidiary, they could consolidate LBA and most of MAN into Jet2 ops, expand at BHX, LGW, LTN etc. and could look at other bases with any surplus aircraft, ABZ, BRS, DSA spring to mind. Even somewhere like IOM might be able to support 1 aircraft if LS and MON were both absorbed into jet2holidays
So essentially it would be 2 airlines, owned by the same company, operating in different markets with as little overlap as possible (except maybe at MAN where they could probably continue operating side by side 70/30 LS/MON to increase capacity), both retaining their identity and flight only side of the business but Monarch flights incorporated into Jet2holidays bookings.
I reckon that would massively boost Jet2, Monarch and Dart group, and the new 737 MAX's would fit into LS's new fleet of 738's
The two operations are near enough identical. Monarch Airlines serves as a carrier for Monarch Holidays, which was Cosmos until last year when they changed name. In fact Cosmos, which was running tours as from 1961 was the forerunner of Monarch Airlines which was formed in 1968 to carry Cosmos clients/passengers. JET2 was first an airline and formed JET2 Holidays later but they are a similar operation to the Monarch Group. The purchase of the Monarch Group by the Dart Group would be a perfect hand in glove acquisition, where as you say, Monarch could continue to operate from Manchester and the South of the UK, as the corporate name is well known both as an airline and as a tour operation, giving the Dart Group an immediate opening in the South of England where the JET2 brand is relatively unknown.
On the other hand the B737MAX order sounds as if it comes with a big price tag, whereas the 30 x B738NG order was probably settled at better prices than Ryanair’s big order. The reasoning behind this is that JET2 are taking the slack of cancelled orders of the NG and as a result Boeing can keep the NG production line operationa until they switch over to producing the MAX. The chances are that more cancellations of the NG will come about and JET2 could well take on the special offers or continue buying second hand NGs, as and when required.