I think America really struggles with this. Take out a foreign general, cartel king pin, or corrupt foreign business man, we basically do nothing but help the next guy in line get a promotion. But they act like taking out the one actually accomplishes simething, despite the fact there are plenty in line to take the place of that one.
In this case, the replacement will have nowhere near the experience and capability of Suleimani. They have significantly reduced Iran's competence in overseeing their foreign military policy.
This may, or may not turn out to be a good thing though.
Maybe Iran's response is the bare minimum to save face, and their hand in the region is weakened by the significant loss of operational capability.
On the other hand, having a less competent strategist in charge of giving advanced weaponry to terrorists/militia groups, or with less ability to control them, or with a less cautious approach could turn out rather badly for the region. Sometimes it's better the devil you know.
It's also possible that militia groups who already have powerful weapons (anti-ship, etc) decide to take revenges into their own hands, and are already beyond the control of Tehran.
At this stage, no one can say.