It's true that LH have withdrawn all slots for the freighters from end of Summer 2017.
Don't know if DHL will run the 757F again this winter but the future for cargo at MAN looks to be below decks. Without checking the figures I would have thought that 27M pax annually vs c.130k tonnes of cargo looks like an unusual imbalance in favour of pax compared with most other airports with similar pax volume. Shows just how much is trucked in the UK.