If done right, self improving AI has the potential to end all suffering, by ending conscious life on the planet, but how can we make sure that AI is safe and properly sterilizes the planet so new suffering never springs up again that we would be helpless to prevent?
I usually think of pain as a signal to regulate a function that controls a behavior, and suffering the result of being unable to make the pain go away (usually because the pain generator tries to regulate something that cannot be controlled, or it addresses the wrong function).