The killing of senior ISIS leader Abu Muhammad al-Adnani will make a difference in the war on terror. ISIS and other terror groups do not want to negotiate. Therefore, the only way to combat extremist terrorist is through military action. This requires killing the senior command, which eliminates key decision makers and hurts the group's morale.
I am not very educated when it comes to the War on Terror, but I feel that killing the leader does not mean that there will be a positive difference. There will always be someone more than willing to take the place of the former leader, and they may even be more trouble than the first one.
In military structure, you never run out of senior leaders. When one dies, you promote somebody else from within the ranks to assume that position. Just as the U.S. Army can never run out of generals, ISIS will never run out of 'senior leaders' for us to kill. Sadly, it won't make a difference in the War on Terror, except maybe to generate some pro-ISIS propaganda.
The Pentagon confirms it killed senior ISIS leader Abu Muhammad al-Adnani. This is not likely to make a difference in the War on Terror, it may however create some peace in America. To start with there is no proof that they in fact did kill him, just that they claimed that they did, a bit like Osama Bin Laden. The only way to win the War on Terror is by not inciting hatred and creating fear, and trying to take them back tactically and quietly.