I think Friday night's historically foolish action by the U.S., UK and France may mark the official start of World War 3.
You could argue it began long ago, but there's always been hope for the trends to reverse. We've now likely gone over the brink, and the odds of turning this ship around is so low it doesn't deserve serious consideration.
Russian leadership are not a bunch of fools, nor will they back down. After Friday night, they know for certain the U.S. empire is determined to castrate them globally at all costs in order to impede an inevitable emergence of a multi-polar world.
I don't think Russia or Iran will respond with a shock and awe attack any time soon, nor will this likely spiral out of control in the near-term. It's more likely we'll see this all play out over the course of the next 5 years or so.