There’s an article over at Comics Nexus that appears to show the original pre-Crisis Earth Two Power Girl returning to the DCU, rather than the one that was featured in Worlds’ Finest and Earth 2: Society who was from the post New 52 Earth 2.
I don’t read Deathstroke (though I hear it’s very good) so only have the article’s information to go on but from the art that it posts, it definitely looks like the first PG is back, purely based on the costume. In Earth-2: World’s End, Power Girl was handed the S-shield of her fallen cousin Superman by the Red Tornado (which was housing Lois Lane’s conscious):
Somehow, the S-shield applied itself to Power Girl’s costume, essentially turning her into Supergirl which goes against her earliest appearances:
Or it would, if they were the same character. The PG from Worlds’ Finest, Earth-2, Earth-2: World’s End and Earth-2: Society isn’t the same PG who is annoyed by the Star-Spangled Kid’s gift. That Power Girl never fought alongside the Super Squad or the Justice Society, but instead had been Supergirl first on Earth-2. She only became Power Girl after being shunted to the Prime Earth following Darkseid’s invasion of Earth-2; when she and Huntress arrived, they found their new home already had a Supergirl, so Kara chose a new identity. They eventually found their way back home to Earth-2, rescued the captured Superman who then died and, as shown above, his S-shield affixed itself to Power Girl, basically turning her back into Supergirl.
However, the Power Girl that is shown in Deathstroke Annual #1, and which the above link refers to, looks a hell of a lot more like the original Earth-Two Power Girl:
Not only is the costume the same as the original’s, but the letterer even uses the font/logo from her 2009 – 2011 series (and if you haven’t read the first twelve issues of that series, you really should) Her series was her last appearance in the pre-New 52 world as the character that turned up shortly thereafter in Mr Terrific as Terrific’s girlfriend was revealed to be the Earth-2 version mentioned above.
So is the Power Girl that’s trapped between worlds in Deathstroke Annual the original, pre-Crisis version? Having long been a fan of the character, I certainly hope so.