The airport is viable for so long as Peel can see a way to make a buck (and they seem to have an eye for it).
The most likely route would seem to be through developing the land. So what does this Teesside brown field site have that other Teesside brown fields sites don't have? "Global connectivity" -
And what do local councils and the other hangers on like - oh yes, "Global connectivity"! So while there's an active runway (and a link to a global hub - bet the KLM contract negotiations are fun...), what better to smooth the way with the LA's and other public/quasi-public bodies.
Sound like a (Master)plan?