Strategy is more or less irrelevant to ISIS. Their "Strategy" is to conquer as much territory and loot as much as possible. They are the modern equivalent of mongol hordes to the people of Syria. That's not to say they can't employ ingenious tactics, just that their "strategic vision" is pretty much rule the world by the sword.
The killing of the pilot is just a manifestation of the absolute violence that permeates the core of their ideology. It really will make little difference beyond possibly hastening their end by a few months. Until a large power from Europe, the USA, Russia, Iran, or China intervenes in a big way, this is going to be a drawn out bloodbath that may end in years of violence after "peace" is declared.
ISIS has one goal: Draw the US into a ground war where they can use gorilla tactics effectively. They are good fighters, when they are in their element, but Obama won't commit troops for them to kill... so they have become very frustrated. Can you imagine if bombs were falling on the US, and nothing could be done about it at all? Thousands of people dying? They are pissed, and with no western nations nearby to invade, they are looking for anything resembling an American to execute.
Mark my words, if we get drawn into a ground war with ISIS it will end with thousands dead for absolutely no gain whatsoever. Undoubtedly we could crush ISIS, but they would continue to suicide bomb Syrian posts. Violence would not end, maybe die down until the US leaves, just like what happened with AQI.
For the record, I believe the execution of Al-Kaesasba was sanctioned by Baghdadi personally. Nobody would undertake this kind of execution with this much preparation and filming and editing without consulting the higher ups. It also probably took a few days to direct, plenty of time for Baghdadi to weigh in on what to do with the pilot. It's messed up, but Baghdadi is basically putting a big middle finger to Obama. The airstrikes are working.
I suggest we continue to bomb ISIS until their economy collapses and the SAA and Hezbollah deal with them. Houthis and Kathab al-Hezbollah already took care of ISIS in Yemen. Fox is whining about it, but it's good for the US. Shi'a arabs are our friends, and we need to work with Iran and Iraq to beat ISIS. Israel needs to butt out.