1033
I think you partly correct in that there is a use it or lose it rule on slot, this was the cause of the Ghost flights uproar a few years back, indeed British Midland at one time had a King Air flying into LHR from EMA for just that reason.
On the other hand slots whilst not technically owned by the airline have been classed as assets on their books, much of bmi value was derived this way.
I think IAG (BA/IB) must be getting very close to the point at which the competition authority would start to have a look and wholesale purchase of bmi slots might trigger that.
Slot sales if they happen will most likely be to other LH companies, probably SWISS who seem to be doing very well at minute or other STAR partners
I assume that bmi have some profitable routes out LHR? I guess in the main mid haul? most seem to think its short haul where the problems are, how many slot pairs are given over to ABZ MAN EDI BHD DUB? do they still fly to BRU/AMS?