Regarding pilots being machine gunned after bailing out. It's a good job that wasn't the USUAL reaction during WW1 & WW2. These people burned one pilot alive I seem to remember. It is just further reason to see that the usual rules do not apply with these people.
Somewhere there is a video of Erdogan saying that a brief incursion of airspace is not reason to shoot an aircraft down. That basically destroys all the arguments from the Turks.
Russia will likely react and regarding IS the gloves are off, even more so than after the airliner incident. Why the US is taking Turkeys side I do not know, NATO and GC does not apply and the best thing we can do if we do not have the stomach for the fight is step aside and let Russia deal with them.
The best IS can hope for is a war between western powers sparked off by incidents such as this. It would pave the way for their caliphate in what is left of Europe.