I adore Pity, and would love to see her join the Marvel Comics canon, but I don't want to see her as a villain. Perhaps the Thunderbolts would be a good fit.
Quicksand is fun. She's like Sandman, only more ruthless. And she did fight Spidey (and Sandman, for that matter) in a 2-or-3-parter in Web of Spider-Man ... a particularly wretched storyline that introduced Sandstorm ... who was never heard from again (but if Slott was willing to reference F.A.C.A.D.E. again, then surely a cameo from Sandstorm is just around the corner).
I would also have loved to see Carolyn Trainer show up in Superior, but was happy just to see Stunner again. That being said, I still think Superior should have lasted at least another year, and that would have given Carolyn ample time to make an appearance. As for Ocks I never want to see again? Carlyle, from JMS' run. He was fun as a throwaway character, but the only reason I'd want to see him referenced again is for Otto to say, "Oh, that guy? Yeah, I killed him shortly after that fight."