Would be very surprised to see EZY leave the MAN 'base.' As people have said, they have bases very close to each other as do LS, FR et al.
For example: LS have four bases within 100 miles of each other. Surely of LS can support NCL, BLK, MAN and LBA on routes across the continent then Britain's biggest airline can support two bases?!
Obviously, launching routes to AGP, PMI, ALC, FAO etc. may work on a daily basis without effecting the LPL network but routes such as AMS and BFS would definately be avoided due to competition and protecting their LPL base.
The point being made about EZY signing a contract with LPL saying that it can't open routes from MAN is absolutely ludicrous and most likely illegal. LPL - a small European airport having a stronghold over one of the most powerful airlines on the continent - really?! If EZY wanted to launch from MAN - they certainly would - whatever LPL say!
The difference between EZY and the likes of Ryanair is that they serve major airports and if they are to receive their 200+ order of busses then they have to put them somewhere, and MAN is a major airport!