[Update: Supergirl has been renewed for season 2, which will air on The CW.]
CBS joined fellow TV networks FOX and The CW in airing its own DC Comics-based TV show in 2015 with Supergirl. However, the future of the series, starring Melissa Benoist as Kara Danvers a.k.a. Kara Zor-El (Superman's cousin), is currently up in the air following the airing of its season 1 finale. Although CBS CEO Les Moonves previously appeared to suggest that Supergirl season 2 is all but a done deal, the show has yet to be formally renewed, even now that the deadline for such a renewal is staring CBS right in the face.
There have been rumors that Supergirl could make the move to The CW - the place that Supergirl co-creators Greg Berlanti and Andrew Kreisberg's other DC superhero TV shows (Arrow, The Flash, Legends of Tomorrow) call home - for its sophomore season. While those claims were relatively shaky in nature, it's now being reported that Supergirl moving to The CW is more of a real possibility and that steps are being taken to prepare for such a change, behind the scenes on the series.
Deadline is reporting that the talks for Supergirl season 2 to air on The CW "are real now," with Warner Bros. TV having already taken steps to cut the filming costs for Supergirl and move the production from Los Angeles to Vancouver, where the rest of Berlanti's CW TV shows are produced. The site also claims that CBS currently has until the end of today (Wednesday, May 11th) to make a decision on whether or not to renew Supergirl, but that this deadline could wind up being extended.
The CW, which is owned by CBS and WB, recently renewed all eleven series in its current TV show lineup for the 2016-17 TV season, including Arrow, The Flash, and so forth. Moreover, the Berlanti-backed Riverdale (a small screen adaptation of the Archie comic book series) is expected to be officially picked up by The CW in the foreseeable future. Hence, if the network wants to have a monopoly on all of Berlanti's current TV shows, picking up Supergirl season 2 would allow the organization to attain just that.
On the other hand, The CW's current DC TV show lineup should continue to be dependable when it comes to delivering a certain level of ratings in the future - with or without Supergirl as part of the package. The CW's TV show roster is likewise quite full at the moment (see those 11 returning programs), with Riverdale being one of the few CW pilots in development that is expected to receive a series order. Hence, The CW may ultimately decide it neither needs nor really has room for Supergirl season 2 as part of its programming slate, even if CBS decides to pass on renewing the DC superhero TV show.
Supergirl would (arguably) feel more at home on The CW than CBS. During the season 1 Supergirl/Flash crossover episode titled "World's Finest" (an episode that made Supergirl officially part of the Arrow/Flash TV show "multi-verse"), a character even half-jokingly noted that the TV show's main protagonists - with Barry Allen (Grant Gustin) in tow - are the sort of "attractive yet nonthreatening racially diverse cast" one would expect from a CW TV series. Of course, the hope is that a move to The CW will allow Supergirl season 2 to actually get made, while at the same time amounting to an improvement on its freshman season, too.
We'll bring you more information on Supergirl season 2 as it becomes available.