EDI meets the criteria
Politically and realistically? Hardly. Glasgow and Edinburgh both have too much civic pride to allow a strategic decision of this magnitude to go forward.
Neither airport is really purpose built for the 21st century, however both are passable local airports. "
local" airports.
I am afraid that Prestwick is doomed as a commercial airport of any significance but I do see Glasgow living on with limited scheduled services on busy, mainly domestic, routes, but predominently as the country's bucket and spade holiday charter airport as well as it picking up most of PIK's cargo business.
Prestwick has never been a commercial success and I don't see how it can be. However the idea of Glasgow taking B744s on a regular basis is not likely.