It has been four years since the debut of Sexy Zone, and being a FIVB group it would usually mean we would be looking at a new group to debut with this year's FIVB tournament. Though that does not look like it will happen like usual as the tournament was moved up and Sexy Zone are once more the special supporters for it. That said it does seem like Johnny's may be gearing up for a late 2015 group debut anyway.
If I were to pick any of the current Johnny's groups I would actually select Kinpuri as the one being set up for a debut this early. They look to fit the image of being a young group with fresh looking faces and more on the cute side. Personally the group does not interest me much but I do recognize there are some talented members that could do well in a debuted group.
Also with the pushing they have been getting recently, like a Music Station performance, it looks like they are being set up for something. Only time will tell if it will be a debut or not.
I love SixTONES, no lie about that. They are the main reason I am still keeping any kind of tabs on the Juniors these days honestly. But I have followed Johnny's long enough to recognize the kind of group they seem to be shaping into and it will not be the one to debut in the near future. They seem to be more likely to be a KAT-TUN/Kis-My-Ft2 where they will spend years as a Junior group before the debut after being built up for it over time. Also once all the members are 20 so there is no worry about underage drinking/smoking scandals or not having a member be able to take on the heavy workload they will need to do to get themselves established in their first few years.
At this point Johnny's has a lot of groups and it seems like it is getting harder for the newer ones to stand out. Kisumai was lucky that they got to be attached to SMAP so soon after debut and gain interest with interactions with them. Hey! Say! JUMP seem to be set to try to copy that formula a bit with them interacting with Arashi much more than they used to. Sexy Zone, I would consider to be a mess with what is going on with their members. So who knows how they will do in the future, but at least they are young enough and selling well enough to stick around. A.B.C-Z seems to be a bit of an experiment as Johnny Kitagawa just could not tell the group 'no' when they asked to debut. Thankfully they seem to have the drive and love for the group to keep things going for them. Nakayama Yuma is a favorite of Johnny so he can count on sticking around just off of that. And perhaps the fact that he is their only recent solo act that does not seem intent to get into trouble. Johnny's WEST right now is stuck with being Kanjani8 2.0, so I do not think many are really giving them the chance they need. On the other hand management seems to be incredibly lazy with the group so there is not much there than the fact they have younger guys in their group.
Any new group is going to have to fight an uphill battle or be very lucky to find their place in this mess. Especially as this is just looking at the newer groups and none of the older groups that are still around and active. So any group that debuts better be willing to fight for any chance they can get to make an impression on the general audience or they could easily be drowned out by the rest already out there.