So looks like Dalaran might be going down in TWW, and Khadgar being lost. With Midnight developing Silvermoon and all the elf races coming together, my suspicion is Quel'thalas and Silvermoon are going to be the new global centre for magic.
All the elf groups will also be involved some how, this includes the night elven Highborne and Nightborne magical groups, neither of which seem to be playing much of a role in Amirdrassil - which to me indicates they will play a role alongside the void elves, high elves and blood elves, and presumably the human and draenei mages will be based there also ..
Silvermoon might become the Shattrath/Dalaran of 12.0 and be a home for high, void, blood, night, nightborne elves. - of the magical persuasion or rather into and centred around magic.