Warning: This article contains SPOILERS for The Flash season 5 finale
The Flash has done more than just tease The CW's Crisis on Infinite Earths, but confirm that the speedsters have changed the future... pushing the original date that the Crisis was supposed to happen up five years. In 2019, the Crisis comes to the Arrowverse.
Fans who have been watching all season have likely already spotted the ways in which The Flash is teasing Crisis on Infinite Earths before it is technically supposed to be taking place. Or, before the coming calamity is supposed to be known to be coming by the heroes themselves. Fortunately, they won't have much time in suspense, now that The Flash has confirmed that the world-shattering event--at least, in the comics--will be coming to Arrow, The Flash, and the rest of The CW's superhero programming.
It may seem like just yesterday that Crisis was first confirmed as The CW's next crossover, leading fans to instantly ask if the TV version would be just as massive and heartbreaking as it was in DC Comics. There it not only brought about the death of Barry Allen, killed off Supergirl, and forever 'reset' the DC Multiverse as readers had known it. Now it appears that the Arrowverse has prepared fans for its own Crisis, and thanks to the season five finale of The Flash, audiences can mark their calendars... sort of.
The tease arrives only in the final button scene of the finale itself, unknown to any of the actual characters. Deep inside the Time Vault concealed within STAR Labs, Gideon lights up the future newspaper proclaiming Flash to "Vanish" in the year 2024. Claiming that the timeline has been altered, the newspaper date updates by scrolling closer and closer, month by month... eventually coming to rest in the current year of 2019. The month is left a mystery for now, but the point is made: the Crisis comes next season. And if the preceding episode is to be believed, it is the destiny of Barry Allen to vanish, no matter how soon the Crisis demands it.
It isn't a total surprise for fans who have been keeping an ear to the ground for any and all Crisis news, but it helps reveal the likely plan The CW and its Arrowverse supervisors are cementing into place. Fans are still hoping to see Supergirl join The Flash's Earth, which would be possible (and those who would rather see Superman die in the Crisis are already having their theories heard). Now that audiences know the next season of Arrow will be its last, a build towards Crisis is making more and more sense. Especially if it arrives part way through the season, as the 2019 date would imply.
Now that the secret is out, expect to hear more open conversation regarding The CW's version of the Crisis on Infinite Earths crossover soon. And expect the story to pick up serious speed once The Flash returns in Fall 2019.