I don't think DS has officially given up on it, although as someone said earlier, there's nothing to stop someone from making their own continuation of it. It's not like DS is likely to sue them or anything.
The problem with someone else taking over is that, as flawed as it is, Big Brother is flawed in very distinctive ways. Someone else would maybe fix the flaws, or flaw it in different ways that might make a better game, but not make it feel like an actual continuation. It would be like watching a sequel to a movie where the creative team has changed. It can have the same characters, but it's hard to capture the feel of the original without the same people behind the scenes as well. TCMS made some great little games based on Big Brother that are actually better than the original in a lot of ways, but it's kind of like two cooks trying to follow the same recipe. They're not going to come up with the exact same result, and even though the second one tastes better, the first one is what you grew up with. So it's kind of cool that TCMS is going to create their own game, because they'll be able to make something in their own style.