The finale of “Crisis On Infinite Earths” restored most things to their proper place, but also made some changes for things going forward, principally the merging of the main Arrowverse earths and the establishing of its version of the Justice League.
Consisting of the principal heroes of the Flash, Supergirl, Superman, White Canary, Batwoman, Martian Manhunter and Black Lightning, the group are primed to face whatever the universe has to throw at them, possibly starting with Lex Luthor’s latest megalomaniacal scheme kicked off by him reinventing himself as a world-saving philanthropist. An eighth seat has been left open as well to represent Oliver, the one who one way or another brought them all together. A seat that will most likely never be filled since the only real choice for his successor, Mia, has been returned to the future.
Having all Arrowverse shows now take place on one earth is unlikely to affect them, and going forwards they’ll each likely pick up where they left off with minimal (if any) alteration, quietly ignoring how history could possibly have played out the same for all of them. However, rather than continuing as a ramshackle assortment of people who occasionally work together to fight larger scale threats, establishing themselves as an official team will afford them greater cohesion. This will serve to bring things closer to the dynamic the heroes share in the comics, where characters appearing in one another’s titles is almost as frequent as their individual adventures.
Not everyone watches all of the Arrowverse shows, but after five episodes of the biggest crossover it’s had in the over seven years of its existence, viewers will now at least possess a working knowledge of any characters they were previously unfamiliar with, lessening confusion should the heroes appearing in other shows start to become more frequent.
With the death (or possible transcendence) of Oliver and the imminent conclusion of Arrow, it’s clear the showrunners decided it was the right time for a soft reboot of the Arrowverse, and establishing a Justice League is the first step in it, promising greater adventures and battles to come. One final thing to note, as well, is that the name ‘Justice League’ was never actually mentioned and so, despite the precedent from the musical tap-dancing duet between Barry and Kara in Flash season 3 episode “Duet,” and the stinger of Gleek the Space Monkey, they’d just better not call themselves the Super Friends.