The following article contains spoilers from The Flash #787, on sale now.
The Flash took a break from his usual story arc for a bit of light fun in The Flash #787 (by Jeremy Adams, Fernando Pasarin, Matt Ryan, Jeromy Cox, and Rob Leigh). An encounter with interdimensional wrestlers from space gave Wally the opportunity to cut loose and take a break from being a hero for just a moment. In the moments between matches though, his new friend, Omega Bam Man, warned Wally that another apocalyptic event was coming for Earth.
While he took it in stride, this is actually more warning than most heroes get about an upcoming event. The warning wasn't specific, only that something capable fo destroying the planet was on its way. This could easily mean a crossover event or potentially another crisis. It's possible this was the Flash's advance warning about the Lazarus Planet, which really amps up the potential damage it could do. Or, even more disturbing, it could be warning about something else that hasn't been announced yet.
The Flash Learned About Impending Destruction - Through Wrestling
As Omega Bam Man explained, WAM, or Wrestling Across the Multiverse, is technically an illegal organization, and as a result needs to be very careful about what planets they choose to fight on. While they do have drones to clean up the damage they do after, it also helps if the population won't be around too long to complain about it. As a result, through unknown means, WAM selects planets that are about to go through an apocalyptic event.
This means that WAM only chose Earth because it was about to go through some other catastrophe. Considering that the story takes place after the Flash's Dark Crisis adventures, it means that something new is on the horizon. The Flash didn't seem too worried because of the frequency Earth experiences similar events, but at least this time he has been warned.
Did the Flash Just Predict DC's Next Crisis?
Now, the most obvious candidate for what's coming would be the Lazarus Planet event that will start in January. A volcanic eruption of Lazarus resin will result in massive changes to the population of Earth. However, it wasn't implied that this would be a near apocalypse scenario. Sure, enhancing an entire planet with powers is terrifying, but nothing that would suggest the world was about to be destroyed. Perhaps, DC was hiding the true level of danger the world is in for the sake of shock value, but if so, then the upcoming event could have much higher stakes than anticipated.
Of course, there is also the possibility that WAM was predicting something else entirely. They never elaborated how they predict that a world is going to end, though it stands to reason it is through scientific means. Perhaps there is something in space heading towards Earth that could destroy it. As the Flash said, apocalypses are fairly common on Earth. One event might lead into another and throw the planet into danger all over again. Still, they have some warning now. They may not know what they're expected to deal with, but at least they can brace themselves.