ISIL Salaries Halved

It appears that the war against IS is having an important economic effect on their funds. Reports are saying the so-called Islamic State have halved the salaries of all members. Apparently monthly salaries range from $400 - $1200 with a $50 stipend for wives and $25 for each child so that represents a big economy drive for the group.

Could this be the beginning of the end for ISIL and would it be fair to say military intervention which has led to this important step has been justified so far ?