I'd like to see Hajime No Ippo and Hikaru No Go continue their series. They're such progression-based anime, showing the characters growing in their abilities to box and play go, respectively. I wanted to see those shows keep up with their manga, but they never did, although Ippo did get one extra season the last time I watched (but there's still a ton more). Also, Berserk couldn't hurt to continue, although from what I hear about the manga, it's really damn long.