Dawdler,
The legal battle between WDC & CVT was certainly unhelpful, but I don't think moving boundaries would help the current situation much. It is also something that applies to airports up and down the land - most are not in the same district as the city they serve. BHX for example is in Solihull, but they are at least part shareholders, so they have been broadly supportive of the airport.
PF - FR went in briefly to BHD, not BFS, which has a longer runway. They weren't there long, but the beancounters clearly judged it worth a go. That is all I am saying - neither of us have technical data to say which destinations are precluded, but Ryanair will. If they have gone into other airports with shorter runways (LDY too), CVTs situation is a disadvantage, not an impediment.
BHX management have been very dismissive of lo-co in the past, they can get it wrong again. BHX also has issues with its own runway for a few long haul routes, although I don't personally think they will recoup the investment in the extension. And they are well out of touch thinking that bringing HS2 into some far-flung corner of the NEC complex is going to make them attractive as London's 7th, sorry 8th, sorry 9th airport!