NA and EU data centers confirmed.

[Suraj]

Would really like some confirmation on this... while I'm EU what I most love is to be able to play with players from different regions.

I wish what we get is what Dannythm said.

[Zumi]

Almost every MMO that has regional servers does it like this, each region has a set of servers for their region which are connected to a set of instance servers which are shared between servers for that region, this makes it so you can have the lowest latency for everyone.

Given that he said players have a choice of where they play it makes me think they would do it like every other mmo. With separate world servers but each region will share the same instance servers for cross server play. I doubt they are going to have some complex mirroring set up like someone thought.