From the wording of the WDA post, and how I understand the new AI engine, they could just make the island exits 'danger areas' for the mobs -- like how they won't go stand in lava anymore (at least in some quests).
Then, the mobs would be following velah's suggestion (or threat if you like that terminology better) that they stay at their guard posts.
At that point, you just give your tank a fearsome robe and tell him to just ignore the mobs..