The one problem with Ishgard as a starting city is the fact that its neighbor zone is Coerthas. The monsters across the bridge are all mid-30s. If you assume there's a direct exit from Ishgard to the new areas then it's possible to make the area just outside Ishgard in the Dravanian lands a low level section but that would seem odd for anyone not a new player. There would also still be an issue with ever travelling to the other city states with the level 30+ Coerthas Central Highlands in the way. The 3.0 story would have to immediately grant a new Ishgard player airship travel to the regular City-States for leveling purposes unless DRK comes in insta-level 30.