The LHR slots never become Flybe's - they remain as a leasehold rather than a freehold. All that happens over time is that they can be shifted from ABZ and EDI routes to any other short-haul route of Flybe's choosing, should it elect to do so. Flybe can also apply for the unused remedy slots at LHR and they have done so for Summer 2019, to be used on any short-haul route of its choice. However, they cannot be sold and cannot be leased to any other airline - so of no value to Flybe unless they can actually make money flying them.