The naval blockade of Ian and destruction of other transport links with the outside world will bring Iran’s economy and government to a halt. The IRGC may then want a deal, but it may be too late.
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By that time, what would the point?
A peace deal or at least an armistice is necessary to set the ground rules going forward. If utterly defeated, the IRGC leaders will still want assurances that they will not be hunted down and killed.