GCE, thank you for a constructive answer. I agree completely - there are too many central belt airports for them to compete, so complementing each other's strengths and weaknesses is the obvious way forward.
My post wasn't intended to troll. One of the few advantages that PIK had over GLA in particular was the perception that they were the only Scottish airport capable of handling full transatlantic (or indeed other longhaul) flights. I appreciate that GLA has hosted Emirates flights for some time, but my understanding is that they are still limited on takeoff weight because of the short runway. I'm willing to be corrected.
I saw PIK as having a real opportunity to get some much needed additional revenue by concentrating on the flights that GLA and EDI can't handle - large, loaded passenger flights - but it now seems that boat has also sailed.