“The Flash” is now in its second season on The CW and it looks like it will be renewed for the next few more seasons. Subsequently, “Legends of Tomorrow” a second spinoff TV series from “Arrow” has just started airing on The CW last month for its premiere season.
The showrunner and cast members of “Arrow” also acknowledge that “Constantine” is part of the DC Comics universe which is the reason why the character John Constantine, played by actor Matt Ryan, appeared as guest star in the fifth episode of its current fourth season.
The one-episode appearance of Matt Ryan as John Constantine actually left the door open for The CW to bring back the character through another guesting stint on “Arrow” or perhaps a possible TV series sometime in the future. However, as of this time, there seems to be no discussion at all about such possibility.
John Constantine appeared on the episode of “Arrow” titled “Haunted” as he was sought by Oliver Queen a.k.a. the Green Arrow, played by Stephen Amell, to help in dealing with Sara Lance, played by Caity Lotz, as she has become a danger to practically everyone after her magical resurrection in the Lazarus Pit at Nanda Parbat turned her wild, unpredictable, and more deadly.