I never understand how they thought they can win a war with just long range missiles that they have no ability to reproduce in large capability in a war time scenario.. The only way that works if there is a nuclear warhead attached to it. Israel cnd just absorb or shoot them all down while suffering minimal human casualties. There is enough past conflicts that they are not too effective on its own. They are more of a annoyance or terror weapon.
IMO, DF alone are not enough in the PLA inventory, it was just temporary copium propaganda hence the current massive aviation buildup.
If it comes to that, where Iran truly runs out of ballistic missiles, and is unable to produce them in large enough amounts, then their last and best option for defense is to goad the Israelis and Americans into invading them directly, head-on.
Attrite them on their own home front, similar to Palestine and Ukraine, and just slog it out using their terrain, tunnels and smaller scale military weapons like ATGMs, FPV drones, etc… to bog down the Israelis and Americans.
The west has air power, but as shown in Vietnam and Korea, underground structures and well-placed, well-constructed tunnels both large and small, and numerous in numbers, can protect you from even the most sophisticated Air Force, even with bunker busters involved.
Russia and China can deliver most of the supplies they need through from the north and east, and they can essentially turn this into America’s Ukraine. They may lose in the end, but will incredibly hurt the west in the process.