As far as geopolitics goes, today is a day of crazy (the Ukranian plane crash, the attacks on the US bases in Iraq, saber-rattling by the top leadership).
However, I believe that things will de-escalate soon. An actual war at this time does not serve any side of the conflict well. None of the players are stupid, as much as people like to think of Trump as an idiot. Iran is a nuclear power, and an all-out war with Iran will only benefit those who sit this one out, namely China, and perhaps Russia.
Islamic countries will make noises as usual, but when push comes to shove, none will side with Iran to face the US, except maybe the Iranian satellite states (the “Shia Crescent”), and grudgingly at that. However incompetent they may be in domestic politics, the American leadership is not crazy enough to think that ground invasion of a nuclear power is possible.
I think there won’t be a WW3. There is no reason to believe that if a war breaks out, it will take place on any theater beyond the Middle East. It would be better for all parties to work on de-escalation: stage bullshit attacks with no casualty, announce some sort of PR victory to save face, do the “Death to America” song-and-dance half-assedly for the home crowds, and open a backchannel to discuss ways to stop things from getting worse. And throw out some Dollars while you’re at it. Obama threw billions to Iran and there was no escalation during his presidency.
I am an optimist, but in case I am wrong, may Allah save all of us.