Since Bleach is on its last Arc, and Naruto is most likely going to end soon as well, SJ is going to need new hit mangas. One Piece is still going strong, but it needs competition.
Personally, even though i'm not a big fan of the new SJ format, i'd like to see improvements in the kind of mangas the magazine includes. D. Grayman, Rosario+Vampire, Ao No Exorcist, Claymore, Reborn, Fairy Tail, Soul Eater, and Psyren are all good candidates.
Mangas like Claymore, Rosario, Grayman, and Tegami are monthly updates. There are lots more mangas, but those are just a few popular ones i can think of off the top of my head.
if you have any input, please comment.