My prediction

3.4 Getting a path cleared into Ala Mhigo
3.5 Us starting to save Ala Mhigo
3.55 Us saving Ala Mhigo and prepping for advancement into the Garlean Empire

Looking at it Ala Mhigo map wise just doesnt seem to have enough there to warrant a full expansion outside of maybe the opening set piece especially if they are carving up pieces of it already for dungeons. Is the entire expansion going to be the size of 1/4 of the Black Shroud? I am fine with getting into the empires territory and using Ala Mhigo as a staging base for these operations.