Loganair apparently do want to operate Manchester, although a bit late to the party so seemingly way down their list of priorities.
IAG claiming their pax numbers are almost as they were pre pandemic but obviously behaviours have changed in the UK domestic market.
However, there is such a clear cost and time saving with flying over the train, that demand can't have evaporated entirely? We're talking about routes which used to serve 500k pax a year. There must be some market remaining- even if it's at 10-20% of pre covid numbers.