Before anybody takes offence, I write this with good intentions. Really, I do.
Debating propensity to travel within Wales and air fares is just tinkering at the edges. A sleepy CWL is merely a symptom. A lousy moribund economy in south Wales is the disease.
Cure the disease, instead of trying to cover the symptom with cosmetic make-up. The medicine is good education and high skills. Medicine takes a long time to act... but once it does, the cure is long-lasting.