Even though CW president Mark Pedowitz has already stated flatly that Black Lightning isn't technically connected to the rest of the Arrowverse, an exchange between two characters on this week's Black Lightning episode suggests a rather interesting way that all might - might - change in the future.
Anissa Pierce and Grace Choi's meet-cute in "LaWanda: The Book of Burial" begins with a comic book - specifically, a copy of Outsiders #16 that's stuffed into Grace's back pocket. When Grace catches Anissa staring curiously, she explains what the Outsiders are all about, and invites her to a superhero-themed party at a nearby club where she tends bar.
In the comics, Anissa (as Thunder) and Grace were both members of the Outsiders who fell in love. The 1995 issue is an obvious nod, but it also prominently features the villain Lady Eve, a character introduced in this week's episode of Black Lightning. However, it's something Grace says that's worth mulling over: Given the party's theme, Grace explains, guests are encouraged to dress up as their favourite capes, and she suggests that Anissa go as either Supergirl or the Outsiders' Looker.
It's already been established that other metahumans exist in Black Lightning's universe, but none of them have been named specifically. However, Grace namedropping Supergirl specifically within the context of a conversation about superheroes and comic books could mean that the rest of the Arrowverse does exist within Black Lightning, but as fictional media. This opens Black Lightning up to a number of interesting options as to how the show might go about further connecting itself to the Arrowverse in ways that would be fun to see.
In fact, the CW itself might exist within Black Lightning. That would make for some lovely meta jokes, but it's also perfectly plausible that Black Lightning himself could somehow travel into a comic book or television show for a Very Special Costumed Team-Up with the likes of the Flash and the Legends of Tomorrow. Or, Black Lightning could go for an even simpler route and just have one of the Arrowverse's many characters with the ability to move through dimensions randomly show up.
Remember, The Flash/Supergirl crossover began with Barry accidentally running so fast, he tore his way through a dimensional barrier. What's to stop him or Cisco from popping through a portal into a world where they only exist as popular comic book characters? Arriving in Freeland would definitely bring those characters down to earth a little, while meeting up with other Arrowverse heroes would absolutely infuse Black Lightning with a markedly different kind of energy.
The question now is what sort of convoluted story arc would it take to make any of this happen?