According to this article, Iran will use its missiles to attack Israel. And Hezbollah is Iran's proxy. N. Korea is in it to grab S. Korea. N. Korea could care less who would win in Mid-East as long as it can secure S. Korea.
As you may know, the purpose of this plan is to split American resources between MidEast and Far East.
We can always wonder if this is 100% true. But it is a feasible plan to me. Kim Il-Sung had been obsessed with the small window of opportunity in which his army can make a dash to Seoul and do not worry about the eventual reinforcement and the counterattack which his army could not beat back.