It's reasonable to consider the counterfactual but it seems like the closest parallel here is Pakistan, which pulled off the gambit successfully.

The years leading up to and immediately following successful acquisition were tenuous and it seemed like they were destined to become a global pariah if not a failed state. And yet now, they are a regional power.

So if anything maybe Iran just missed its window. Now with the US seemingly ready to enter a forever war with no defined objectives other than nuclear deterrence it's presumably too late, but maybe a more competent regime could have pulled it off in time.