After the debut of Marvel's Agents of S.H.I.E.L.D on ABC, superhero universe crossover were no longer restricted to the big screen or printed page. Opening a chance for high profile team collaboration on network TV, in the end, the CW applied the made platform of Arrow to premiere their highly acclaimed speedster exploration of Barry Allen (Grant Gustin) even before The Flash TV series in the premiered. At the time, viewers have been treated to other shared universe events, both Felicity Smoak and Oliver Queen have a short guest appearance on The Arrow and The Flash crossover plot which is set to premiere a week from now.

On the other hand, with the CBS announcement, Supergirl TV series from Flash and Arrow producer Greg Berlanti, there were speculations among the fans whether or not they will be seing Kara Zor El cooperating with Barry and Oliver in a crossover event of the three TV series.

Currently, only a couple of months ago Supergirl TV show was announced officially. Finally, Berlanti is weighing-in on the discussion, saying the it is probable that fans will get to view the Supergirl in CBS along with The Flash and Arrow in CWs.

A possible Arrow/Flash / Supergirl crossover was teased in the most current issue of Entertainment Weekly, which development is detailed on the incoming Supergirl series:

Later in the afternoon at his other office on the Warner Bros. lot, Berlanti meets with fellow producer Ali Adler and Oscar-winning costume designer Colleen Atwood to go over looks for their upcoming revamp of Supergirl. The show will follow 24-year-old Kara Zor-El, Superman's cousin, and with a twist that that could melt fanboy brains, Berlanti says it's possible this Supergirl could enter the worlds of Arrow and The Flash.

Furthermore, Berlanti, Atwood and Adler are presently playing with their options of Supergirl's costume, although, it was made clear that, Fox's Gotham Supergirl could be present in the same universe as the Arrow and The Flash.