Since experiencing a deluge the day after the event ended in 1998, I know that the end of Burning Man will be a massive rainstorm at the wrong time.
Fortunately in 1998 it happened after almost everyone had left. It was Tuesday after the burn, and we were packing up. Clouds coming in from Gerlach were worrying, we could see the downpour happening over there and heading our way rapidly.
We closed the trailer door as the rain started. It came down so fast that by the time we were half way to the road it became almost impossible to drive in the mud, we were jackknifing with the trailer, almost losing control. There was an RV also racing to the exit that I witnessed doing accidental 360 spins in the mud, they totally lost control of the vehicle. I'm not sure they made it out.
I heard that the heavy rain continued for a few day, and the cars that were still there sunk into the mud. If you didn't get out before the rain, you were stuck there for weeks.
Now imagine this happens on Saturday, burn night. People have gone through almost all their food and water by then. Then the rain makes it impossible to leave, for weeks. All the vehicles sink into the mud. You can't even really walk through that mud to make it to the road, because it sticks to everything. "Playa platforms" are what you get when you try to walk through the mud. Now add 70,000 people, running out of food and water, and unable to exit the playa for possibly weeks? That's National Guard rescue territory. I doubt Burning Man would be allowed to continue after that.
Ever since 1998 I watch the weather closely, and you can bet I'll be the first one out of there if it's looking serious.