A new look into ISIS. Is this a real threat yet, or is this something that can still be put back in the bottle?

A german journalist jsut returned from 10 days with the ISIS. His account is formidable without the flavoring words found in most reporting now days to appease an editor. His view is two sided and provides us with our first real look into what appears to be a functioning society...albeit a brutal and barbaric one. His notice of the way in which the fighters are spread indicate that they can withstand our air strikes indefinitely unless we are willing to go back to WWII style bombing. What now?