After the successful inter-network crossover between The Flash and Supergirl, executive producer Andrew Kreisberg was asked if there could be an Earth-1 Supergirl appearing on The Flash. When asked about a Kara Danvers in the CW universe, Kreisberg said:
Any Kara that exists on Earth 1 would also have to have been an alien. It can't just be Kara Danvers from Poughkeepsie.
Sure, different costume, but sure.
Which has lead a lot of fans into thinking he is talking about Power Girl. The character of Power Girl is basically an alternate reality version of Supergirl anyway, so it would make sense that a Kara from an Earth without a Superman like Barry and Oliver's or Earth-2 wouldn't necessarily take on a Super-related name.
If that is in fact what Kreisberg was referring to remains to be seen.
[Source: Entertainment Weekly]