Silverstein didn't give away many of his secrets, but he did mention that Season 4 will explore more of Nikita's pre-Division origin story. Similarly, we haven't heard the last about Amanda's past. Because Amanda's true identity "Helen" never existed, she's obsessed with molding lives like Nikita's, and her work with The Shop will take this to a new level. And while Nikita has decided she must kill Amanda in order to exorcise her own demons, Nikita will have to come to terms with the darkness that was a part of her long before Percy and Amanda got their hands on her.
Shane West said that "Mikita" will start off in a rather dark place. Nikita's decision to go rogue yet again will test their relationship. When he mentioned he'd like to find out Michael's last name before the end of the series, Silverstein said it appears in a deleted scene on one of the Season 3 DVDs that will be released in October. I'm about 80% sure he was serious about that. He also discussed how Amanda was slated to die before the end of this last season but she was "to evil to destroy."
Devon Sawa couldn't make the panel, but Sam will be back. Circumstances will bring him into Team Nikita's orbit, but he is still a volatile and unpredictable piece on chessboard. Silverstein also hopes there will be enough time to bring back Isaiah Mustafa's Cyrus as well as Ramon (Simon Kassianides), the paralyzed spy who helped Nikita save Michael in Season 2's "Knightfall." When a fan suggested bringing back Percy in flashback, the suggestion was met with great enthusiasm by the audience as well as the assembled cast members. Whether or not it will happen is just one more thing Nikita fans will have to wait to find out when Nikita returns, probably in late Fall.