ISIS received a message after its number two leader died of wounds inflicted from an attack. The group only understands violence, and this lets its leaders know that the world will find you, and a price will be paid. This worked with Al Qaeda, after its leaders kept getting killed.
The death of the number two leader will send a message to ISIS. Unfortunately the message may not be what the world would like it to be. Most likely the message they will derive from his death is to double forces and increase resolve to terrorize any that disagree with their ideals.
Unfortunately, I don't think losing anyone in the ISIS organization will "send them a message". I think they're going to continue their fight no matter what, which is a scary thought. Terror organizations don't care who they lose. They will push forward no matter what because message of hate and terrorism has been so ingrained in their minds.
What an interesting job as an ISIS leader. Recruit people to kill innocent civilians, insuring a nice warm spot in hell at your death, and then knowing you probably have a shelf life of about 3-6 months before you are blown into fragments. You would have to be dumber than an ISIS member to be an ISIS leader, and that is hard to pull off.