But only it seems as Karen Starr, since DC seems to continue to go out of their way to refer to her only by that name, rather than as Power Girl...
 
And she's one of only three JSAers to make the jump, along with Mr. Terrific and Hawkman.  The rest will be "resting", at least for a year it seems.  What role Karen plays in Mr. Terrific haven't been revealed.  Why they won't call her Power Girl also hasn't been revealed...

maybe she'll help him run his company

Maybe, but doesn't seem so from the later news from the Justice League panel:
 
Power Girl may or may not exist in the DCnU, but Karen Starr does, and you'll see her soon.
 
and:
 
Karen is "a little bit different".
 
and:
 
Karen shares a connection with Holt that will be revealed later.
 
From these very sparse tidbits I conclude that Karen is:
 
Probably a continuing cast member of Mr. Terrific, or at least recurring cast.
 
might also show up in other books like perhaps Voodoo from time to time.
 
Isn't the tech mogul we know and love, but something else---some sort of government agent perhaps, based on the cover to Voodoo #2?
 
Can't say what the connection is yet.  Can't say if they mean for Power Girl to exist or not in the reboot.

Maybe she'll be Holt's romantic interest.

Maybe she'll be Holt's romantic interest.