There's no information yet on the multiplayer maps for Black Ops 2 so at this moment it's all speculation and guesses. In my opinion, It's definitely possible that Nuketown might come back on Black Ops 2. Although it may be in the form of a DLC like how Hazard in the annihiliation DLC was a remake of the Cliffside map on World at War.
I really liked nuketown, it's probably one of my favorite maps so I would really like to see it comes back on Black Ops 2 too. It'd be especially cool if it's like Nuketown 50 years later. But if Nuketown doesn't make it back, I am sure there will be a "small" map in Black Ops 2 that resembles the chaos and gameplay of nuketown.
EDIT: It does look like that Nuketown will be back in Black Ops 2 as Nuketown 2025
Also looks like it will be a DLC that is free for those that preorder the game. :D!