The market does not yet see this as a probable outcome which is why it the issue is currently under-appreciated and not being discussed as much as it should and soon will be. This is not unusual; markets typically only start focusing on large macro events AFTER they have already occurred.
Great question, Maggie Gab: There are two main possibilities. The first and most important possibility is to score a quick "knockout" victory such that the Iranian regime is overthrown by their own citizens, the war ends and the Strait is reopened. The second possibility is for the US to aggressively enter the war early on and help to secure such a "knockout" win. As long as the current Iranian regime is in power and has command of Iran's military forces, they will be able to threaten commercial shipping in the Persian Gulf. Therefore, the key to a quick reopening of the Strait is an overthrow of the regime. This is, of course, a very difficult task.