I don't think the gap is closing personally - EDI should be achieving 12 million pax this year, and GLA will probably be around 9 million ish which is a fair difference.
Having said that, a strong GLA and EDI is great news for Scotland and it's good to see them performing so well.
Gordon Dewar talks of the many hubs model and I believe this is the way forward for both airports rather than relying on the likes of BA or EK as the dominant carriers.