I would say one anime that could benefit some form success if it received the right marketing would be Hajime no Ippo. Black Lagoon could also benefit some sort of short term success on Adult Swim, but we know how much they love anime.
As for the shounen trinity, Bleach is still relatively solid, Naruto has been dead in my eyes, and One Piece has so much potential but will never see the light of day thanks to its tarnished first impression, and CN's stubborness. In terms of finding a brand new ultra mega hit anime, then I don't see anything at the moment.
I think the reason why CN isn't willing to air anime anymore is because they have pretty much sucked that particular 'niche' dry.
I mean, after DragonBall, Pokemon, Yu-Gi-Oh!, Naruto, Bleach, One Piece, Sailor Moon, Gundam, Voltron, Robotech, Gatchaman, Speed Racer, Rurouni Kenshin, Yu Yu Hakusho, Saint Seiya, Ronin Warriors, Tenchi Muyo!, .hack, Hamtaro, Cowboy Bebop, Samurai Champloo, FLCL, Ghost in the Shell, Evangelion, Fullmetal Alchemist, Inu Yasha, Astro Boy, Gigantor, Lupin III, Big O, Detective Conan, Shin-chan, Death Note, Code Geass, Hayao Miyazaki films, Animatrix, Batman: Gotham Knight, and many more, what other highly successful anime series could CN give a chance in order to make a big hit? And even if they did fiind one show, it would come and go, and be viewed as a waist of money in their eyes.