Okay so let's take it on the gospel truth that they will be acquiring the A330's. Let's also take it that they acquire a handful of A330's from Air Berlin but not the whole fleet.
Side Note: If they were to acquire the whole of Air Berlin's A330 fleet, at 17, that would put them ahead of Thomas Cook (6) TUI (11), even ahead of Norwegian, and slightly behind Virgin which was 37 aircraft in it's fleet.
So it acquires let's say 8 A330's for appeasement sakes. Where would these A330's be based would be my first question?
Manchester would probably be the first suggestion, very large and in some parts very affluent. Can offer some form of competition against Thomas cook to an extent and was where they operated from when they had the 2 sole A330's.
Birmingham would probably be next suggestion. Allows the airline to grow long haul into this airport and hopefully keeps Norwegian out of BHX, similar to TCX at MAN. Probably the only real sound suggestion however going in with 8 A330's into this market would probably be too much too soon.
London Gatwick is probably off the agenda. Already going up against VS and BA, TCX & TUI, Norwegians very large presence probably doesn't help in this situation. Yields are probably trashed on some routes, competition fierce on others (Caribbean, TUI, TCX, BA VS, America BA and DY) just generally a no go zone for an airline that give up the long haul and isn't really growing at LGW.
Luton - Don't see them adding long haul to this base.
Leeds/Bradford - Ha you've got to be kidding me. LBA Long haul. Also going Long haul in Jet2's back yard.
So then next is what would the route structure be? Caribbean, Florida, Long Haul holiday would be good bet. However they've retracted from the inclusive tour operator offering that they once had so that would require a substantial amount of investment from Monarch including setting up tour operators in the Caribbean. I would also predict that TCX/TOM have now taken this market by storm offering significantly improved on board products and both are well known. Monarch would be the new kid on the block with this sort of offering.
That then comes to the next market; long haul low cost. This could work, LAX, SFO, LAS, ORD, BOS, JFK, IAD, MIA/FLL, MCO would all probably work from BHX/MAN but where next?
India - DEL, BOM?
South Africa - CPT? JNB?
Thomas Cook/Virgin have most of the markets covered from MAN to America, the ME3 and the EU3 have Indian/South African markets covered.
There is very limited markets that Monarch could enter with the A330's apart from the BHX-US market; maybe MAN-US. Most other markets seem have what can be classed as traditionally 'Full service carriers' covering them with plenty of options.
TCX seem to have the 'Low cost' carrier presence MAN and doing well out of this hub. Norwegian seem to be doing alright out of London Gatwick. I just think that Monarch are heading into very dangerous territory (territory it once knew however the ball game has changed completely) that has led several great airlines to their demise. Monarch should stick to what they are doing at present, in my opinion, grow with the routes that they offer and into new markets previously untouched by Monarch and perhaps add a new base somewhere (SW England?) going into regional bases that easyJet won't touch.
On and to put the rumour to bed here is the latest article from Reuters.com:
https://www.reuters.com/article/us-air-berlin-lufthansa-timeline-idUSKCN1B90Y2