The Edinburgh Airport Rail link was a great idea and should have been given more consideration. Many airports on the continent have direct rail links to other parts of their country and not just the city served, Zurich for example. A rail link at Edinburgh airport would serve the central belt, Falkirk, Stirling and on to Inverness, Dundee and Aberdeen would be linked via the Forth Bridge, Glasgow (Queen St) via the new spur to the existing Forth Bridge/ Falkirk line and of course in the opposite direction Edinburgh and the south, plus the new Borders rail line when completed.
Edinburgh airport can expand and a second runway can be built when needed. Whilst Glasgow and Prestwick can also grow, Edinburgh can become a truly international airport for Scotland.