Previously Khamenei could disrupt Iran’s government in the past, if the success of those governments was considered bad for his regime. Not anymore. If economic problems persist, there will be huge social unrest. Khamenei’s main problem is at home not abroad. These people are not soldiers to fight for Khamenei’s ideals anymore. Khanemeni will have no other option but to improve the economic situation.
UPDATE 1:
In the case of any conflict, Iran will see huge social unrest against a regime involved in a war with other countries. Those huge social tensions will surely encourage social unrest in the home countries of other countries involved in a war too.
UPDATE 2:
This won’t be like WWI or WWII. If World War 3 starts social tensions form a separate front. In WWII countries fought against other countries not their own people. In any scenario for World War 3, Iran will be involved and Iran is at the edge of social collapse. Remember Arab Spring started in Iran. No one wants such a partner. No one wants such a war.
There is only one option, Iran should be the bridge between east and west. Iran benefits. The West benefits. China benefits, and everyone else benefits.