Now that was a pretty good article. It simply reported the news and didn't offer opinion of who was right or wrong. Regarding the area they are talking about, from a military perspective it makes sense to try to hold that area but affords little protection. Personally, I think they'll melt away after Raqqa and manifest themselves in another form elsewhere while carrying on low level terrorist activities.
Iran is not interested in stability in the Middle East, at least not at present. They prefer instability because that is bad for us since most of the countries in the region are friendly to us to some degree. They hope to destabilize the region and then re-stabilize it with governments that are friendly to hem and unfriendly to us. They would love nothing more than to topple the Saudi monarchy… that would be a huge coup for them.