It's happening! DC Comics has confirmed that Supergirl would indeed crossover with The Flash and Arrow!
The official DC Comics Mexico Facebook page has revealed that Supergirl would be part of the CW Justice League.
As you can see in the post below by DC Comics Mexico, the CW Justice League's members are Robbie Amell's Firestorm, Brandon Routh's Atom, Stephen Amell's Arrow, Grant Gustin's The Flash and Supergirl.
The post of theirs begs the question though, is this our first look at Kara Zor El and the Atom?
While this is concept art level at best, it makes it a bit confusing as to why Kara Zor El's costume is similar to the ones used on Man of Steel given that the show is not tied in with film at all. Perhaps DC has an answer to this in the future,
Meanwhile, Greg Berlanti admits that the Supergirl TV series should hold its own as show first before planning crossover events.
"So much has to go right for us to be able to make a great show. Again, I think of myself as like if I were watching them, I would want to see that. But we have to get so many things right to make a good show and so much of it is luck, unfortunately." Said Greg Berlanti to IGN.