The Iranian regime is unlikely to fall if the only dissent is mass protests. They have weathered enough of these in the past and are hard-headed enough to continue to do so.
i think the only way this evolves into significant change is if a senior figure, or more than one, in the IRGC decides that they have better prospects if they back the current President, or even the exiled Crown Prince.
It would be far more preferable for the civilised world if the protest organically led to a truly democratic, secular revolution. However, the military, and in particular the IRGC, hold the most leverage.
What is worse is that any outside assistance could plunge the region into chaos, which makes it extremely unlikely that any help is coming for the protesters.
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