An Iranian's analysis:

Hussein Ali has died. Good.
But I have family in Iran. My father is there right now. So I can't celebrate yet. Here's why.
Iran has developed the most rigorous emergency plan on Earth to respond to this moment. Each critical position has a four-tier succession mechanism. Military strikes are authorized in advance. Regional commanders can act without orders from Tehran.
By the time you read this article, a new Supreme Leader has already been born. We just don't know who he is.
This is not Maduro. The government has not been overthrown. The system has endured a shock. That is precisely the design intention of the system.
All credible intelligence assessments point to the same conclusion: post-Hussein Ali Iran is more likely to become more hardline rather than more moderate. The Islamic Revolutionary Guard Corps will be more active, more dangerous. For the Iranian people, this could be worse than Hussein Ali himself.
Don’t breathe yet, the road is still long.