Hah, this is great, some concrete casting news!! And now, Topher Grace, Electro, or Venom? Definetely not Ned Leeds, I hope.
But seriously, if they have Venom and Sandman in the same movie, i can't see how they could possibly play off each other. Unless the Sandman is just gonna be there just for a minor pre-credits fight. Or if they screw his character up like they screwed up the Scarecrow in Batman Begins.