But keep in mind that the very large T2 extension to the West uses the piers model also. MAG's plans call for these to be brought on stream to accommodate existing demand before (smaller) older sections of the complex are withdrawn for development in sequence
That's precisely my point SHED. As the work is undertaken to add those piers, there will be a significant drop in apron and gate capacity for the duration of those works. There is every chance you will have lot's more terminal space but nowhere to park aircraft at various stages of the construction.
Also, you do keeping repeating about the 'very large extension' to T2 as though this will make everything ok. To put things in perspective, whilst a 140% expansion is an impressive figure you have to bear in mind the starting point, i.e. 140% of what. Believe it or not the core 'terminal' part of T2 (i.e. excluding the gate area along the front) is only a couple of thousand square metres larger than Liverpool's terminal in terms of footprint.
Apart from the obvious, determined by the location of US pre-clearance facilities for example, it isn't advisable to micro-manage airline terminal distribution so far ahead.
I would have thought that having a vague clue whether the redesigned facilities can actually accommodate their customers effectively would be essential before embarking on the construction phase? I suspect if MAG turned round to Ryanair or Easyjet and said "we'll think about where you're going nearer the time", the response would be unprintable...