I'm no expert in geopolitics, but to me the relation between a nuclearized Iran and Saudi Arabia could become like that of North and South Koreas: tense but ultimately passive.

That relationship is (was?) a proxy for two mature superpowers. The dynamic between the mid-tier powers in the Middle East is not that similar, IMO. With the US realigning, I expect to see more activity in that conflict.

I can’t know the future, but if the model I’m proposing is correct we’ll see some NK/SK shake-ups soon. That won’t bode well for Iran.