LLAL's cram 'em in at all costs attitude has certainly led to the decline of heavy aircraft maintenance at LTN. I can't see any serious takers for the ex Monarch hangars as the parking restrictions already mentioned will prove too limiting. As it is, TUI have to wrangle with the airport on a daily basis during the busy hangar season to come up with a plan to shuffle aircraft around and deal with arrivals and departures.
Unfortunately the days of the hangar line being used virtually exclusively by Monarch and Britannia hangar aircraft with the odd cargo and ad-hoc aircraft are just a fond memory!