What does the best case scenario look like from here?
Best case for who?
The crux of this is that the Iranian govt wants nukes and is prepared to do what ever it takes to get them.
The rest of the world don't want Iran to have nukes.
The USA is prepared to hold sanctions on Iran until it gives up its aim to have nukes and thinks it can force the issue economically.
The Iranian govt is in trouble for the first time domestically because the economic hardship is forcing a wedge between it leadership and the people who are paying the cost of its desire to have nukes and oppose the US by spending billions on proxy forces across the middle east.
When sanction go on the US got the blame but as the economic damage mounts it is inevitable that people question whether its all worth it to them. The Iranian govt is in a bind if they can't escalate this further they are in danger of falling, you can't keep shooting thousands of people to stay in power and expect to remain popular unless you can show your external policy is working. So they attack Saudi's oil facilities and the US embassy.
So the US kill the two most senior generals who made that decision.
Best out come for the US is the Iranian regime falls.
Best outcome for Iran is US overreach and ends up changing its policy following massive casualties because that is the only way they will change their policy on Iranian nukes.
Best outcome for the rest of the world depends on whether you could live with several nuclear powers in the middle east or not.