HUY has survived on just AMS, ABZ and Heliport traffic in the winters for many years - Its the charter traffic that has changed, as operators have gradually consolidated flights between HUY and DSA - and generally opting for DSA. I can't see HUY or DSA shutting up in the next 10 years (hopefully) as the both seem to operate in different markets, Humberside has a large amount of Helicopter traffic, and supports Humber businesses with worldwide connections via AMS, and of course its Aberdeen link - all of which are showing growth (AMS and ABZ figures are both up in the 5-7% area this year), whereas DSA has taken up most of the sunshine routes and Lowcost (wizz).
Think the consolidation of pax traffic at DSA is related to (1) a larger population catchment area in and around Sheffield rather than in the Hull/Grimsby areas; (2) it's only been possible in the last few years as civil aviation at DSA is a fairly recent development; and (3) regretably SZD never took off as local/regional airport, it was always a niche airport with insufficient "niche" (too small?).
Teeside on the other hand is looking much riskier having recently thrown out its last remaining charter flights, and seems to have falling passenger figures on its remaining scheduled services.
Yes, chucking airlines out does look like a suicide mission. The airport management appear to have "lost it big time" since BD left. What on earth is going on at MME?