A TCX's A320 based in HUY would be definitely work fine, during the whole summer season, May to October.
They should aim to offer flexible stays and departures to the best-seller destinations, such as Dalaman, Larnaca, Tenerife, Heraklion and Palma, offering at least 2 weekly flights and, in the meantime, flight-only tickets to the increasing public made by second-home owners, DIY travellers and so on.. and I guess filling almost all the available seats would be an easy game to sustain, maybe also sharing this capacity with rival firm Thomson, as they are frequently swapping their own seats each other, from other UK airports.
Next to these flights, they should consider to include some others that are registering an increasing popularity like Paphos, Monastir (Tunisia) or Sharm el Sheikh, to name few. Plus operating also some Ws to other smaller UK airports.
But first of all, what they need is a full support of local travel agencies and also from the Board of the airport. Holidaymakers have to be addressed firstly to HUY if they want to travel to the offered sun spots and these could be reached only with an intensive work of promotion throughout Internet travel sites and holiday agents, alongside with a very reliable schedule of flights.
As for Costa Blanca (Alicante) or Costa del Sol (Malaga), as well as Algarve (Faro), the best way to regain this traffic and give a boost to the airport, is to attract back again Ryanair.
A 738 with a low-cost pattern is more suitable for these destinations, rather than Dublin was.