http://www.onlysp.com/2012/07/05/halo-2-anniversary-actually-happening/
“In the latest Official Xbox Magazine, a spot in the magazine where rumors are usually reported, stated the following. “Following the success of Halo Anniversary remake, 343 Industries has now started development of Halo 2 Anniversary.” The little snippet of the article will be pictured below. Keep in mind that this is only a rumor, and until subscribers get the actual magazine in their hands we won’t be able to confirm this to be true. However, Halo Anniversary did sell around 1.5 million copies, so it wouldn’t be far fetched to think that 343 would have the intention to bring Halo 2 back as well. Maybe they’ll even incorporate the MP maps into Halo 4 as Halo Anniversary did with Reach. Make sure to follow OnlySP to keep up to date with this rumor, we’ll try to be the first to let you know. We’ll be grabbing an online copy of the mag in the next few minutes to try and confirm this, I will update when we know for sure.”