Volotea has smaller aircraft and slightly lower fares by the look of it (on occasion), and Jet2's city routes from NCL seem to be trundling along slowly with numbers decreasing bit by bit until they decide it's not profitable anymore and pull it... Look at Cork... However that is now working quite nicely with Aer Lingus. Just because one airline cant/wont make it work doesn't mean another cant give it a go.
With regards to the runway extension, it's not necessary, if aircraft are performance limited, such as the A321/738, why not keep the 757's as long as they can until the neos/max's come out!!! (Only half joking)