Though I am not a fan at all of the New 52, it's pretty clear: those two should go back to Earth-2. In this new universe, having both Supergirl and Power Girl in the same space just diminishes the unique situation PG has. Here's my idea:
If James Robinson hadn't already penned the introduction of the new Earth-2's second Batman, bringing PG and the Huntress back to Earth-Two would be an easier means of giving that earth back it's Bat-Family representative. Both she and PG could succeed their late father and cousin respectively, and with the addition of the new Fury (who, like the Pre-Crisis Infinity Inc. member, is WW's daughter), Earth-2 would then have its trinity. BUT, Robinson can still stick to his guns and let the new Alan Scott, Jay Garrick, and Hawkgirl take the lead should the JSA be formed, and with the addition of the new Dr. Fate, Al Pratt, Wildcat, Captain Steel, and the aforementioned trinity, you've got yourself a JSA that's good to meet the Nu52 Justice League.