I do hope that if they do release an AoE mitigation tool for WHM it's a new spell or ability in 4.0 and not a modification to the existing Stoneskin II. The intent of Stoneskin II at the time was introduced as a QoL change to allow for raids to setup faster and given to WHM's for free as a QoL. I feel any buffs to Stoneskin II would generate a lot more outcry from the rest of the player base than praise from the WHM players.
[EDIT] Also you're going to need to do more then just make Stoneskin II usable in combat to make "WHM on par". WHM is actually quite viable in its current iteration but there are some glaring flaws in balance logic when you compare the WHM kit to a Diurnal AST kit and additional mitigation isn't the solution to that.
