Unfortunately now that we have DSA i don't think HUY would attract a true low cost carrier to have a base there anyway, i.e EZY FR etc...
As said before if LS were to base at HUY i guess it would focus on holiday routes such as those it offers from EMA, attracting travel agency's and tour operators. XL showed it to be successful in this market a couple of years back and was set for an increase ind estinations the following summer (however it obviously never happened due to other reasons)
At a push, HUY could offer hi-frequency med routes, however the airport is less suited to handle a huge increase in traffic at present. DSA on the other hand is slightly ready positioned for this, its ready to go and has already proved itself popular on the low-cost high frequency model.