I disagree on why Wizz pulled out. They were establishing new routes but at the same time being beaten up by not enough crew/planes at the established bases. They made a logical decision to concentrate on those (Doncaster was not the only airport they pulled from).
If there was good money to be made, Wizz would have found away. The speed with which they dropped DSA suggests forward booking where marginal.
If Peel have put money into the airport over all these years just to get hold of the land, that seems a rather optimistic interpretation of the value of brown field sites in South Yorkshire. I've heard of playing a long game, but blimey...