Considering the allegations of active support of ISIS by the US and Turkey, isn’t it more probable that such organisations are being used by super powers to achieve their strategic objectives; and their threat level is deliberately exaggerated.
Any comparison among the economic, military and political power of the three super powers the US, Russian and China will demonstrate that any alliance between Russian and China will leave US far behind even if counting in the resources of its allies like UK and France. But from the perspective of third world war, its immaterial which side is mightier than the other; as the real reference point for debate on any such war is whether human species will survive it or not. If world powers fail to contain this war and reach some political settlement on Syrian question, full-scale third world war cannot be ruled out.