About Stealth Symphony, if Soma's any indication, I think this might serve to be a great comeback for Amano. For however unsuccessful it was, Akaboshi already seems to have developed a following. I presume it's partly because it was based on a Chinese novel. The collaboration with the author of Durarara should probably only make things better from there.
Nura was even more renowned, so although it kinda feels a bit soon for Shiibashi to return, I think Illegal Rare can still achieve some success, especially since it seems to be venturing into a more darker storyline. It's risky, but it's also something none of the other series in the manga seem to want to touch.
Seeing a new soccer manga like Tokyo Wonder Boys could definitely appeal to fans of the sport, but it can still face some heavy competition from Haikyu and Kuroko. Also, I wonder how fans will perceive a new soccer manga after WSJ decided to flood the magazine with soccer manga back in the turn of the decade? Though if Kento Shimoyama's involvement means upscaling the art to anime-quality, it might still achieve some sort of following.
Finally, if Nisekoi can fend itself off from Koisome and Pajama at the same time, I don't think it'll have too much of a problem sucking the competition away from iShojo, especially with the ongoing debut of its anime.
So in decreasing order of success, I'm predicting it'll turn out like this:
1. Stealth Symphony
2. Illegal Rare
3. Tokyo Wonder Boys
4. iShojo