At least for volume 4 and what the characters are doing.
Ozpin: I'd be surprised if we get much of an appearance. He probably will not be around as much as he used to be. The idea of him being gone make a gap for the wise mentor and creates problems. From a storytelling perspective that needs to at least be explored.
Team RWBY: Likewise I can't see the team reforming so soon. I think season 4 will explore them as individuals more.
Yang: She will have to pick herself up or be pushed. I could see either her dad doing it (since he lost too many people he loved already) or her mom. The plot with Raven has been dangling for awhile. Last time she was mentioned Qrow claimed he could help Yang find her. I'm guessing he already told her how since I can't see her letting that go. If she gets a new arm she'd likely go to Atlas to get it. I can't see her training while she was in her depression so she has to get back into fighting form if that's the case. If Raven is involved I think that's a lot of tough love.
Weiss: Family drama with her father has been hinted at for awhile so we'll finally see how controlling he is. Judging by the artwork I think he has been especially controlling lately since her "rebel" side ponytail is gone. There's also a lot of potential met ups with people from Atlas like Winter, Penny's dad, General Ironwood or team FNKY.
Blake: She is either hiding from Adam or taking on the White Fang. By ditching her friends Blake thinks she's protecting them. I don't think she'd be in Vale if she's pursuing the White Fang since I recall Adam mentioning returning to a different area in the flashback episode. Implying it's his home base and I think it's around the same area RJNR are in.
Sun and other students from different schools: Either trying to go on their own missions or going to meet the main cast. I'm not sure if anyone will believe them if they tell everyone it wasn't an act of war. I'm not even sure how much of the truth they know.
Nora: I'm hoping with Pyrrha dying Nora decides to tell Ren the truth. It would be great to hear more about their backstory and see the RJNR team bond.There's a lot to them that hasn't been touched on.
Ren: I think he's one of the only people we've seen fight without weapons and do it well. Given Jaune' s learning curve and Ruby' s trouble with weaponless combat Ren needs to train them. I also like to see him being more social.
Qrow: He has quite the gap to fill by taking over where Ozpin left off. How much does he know compared to Ozpin? Ruby says Ozpin reminds her of her uncle and he did tell her where to go next. Will he be staying in the shadows as he follows RJNR? Or will he be meeting up with them to train them, share information, etc ? Qrow told Ruby about her powers but he didn't say anything about the real danger.
Ruby: I'd like to see Jaune and her co-leading the team. I've heard some say he's too traumatized but Ruby also lost Penny and her team split up. Just saying it's not just him who's suffering. Anyway I'm really excited to see how this team interacts. I think that's the thing I'm most looking forward to as it fleshes out their relationships further. If Qrow does make his presence known Ruby might ask him for more information on her mother. I don't think we'll find out much but her death might be a hint of things to come.
Jaune: By this point Jaune must have improved a lot. Remember what Qrow said to his nieces? That everyday outside was worth a week at the school? While so time has passed I'm curious how Pyrrhas' death will be dealt with. Plus the fact he knows something is up since he knows the school was hiding something in the vault. Needless to say I'm also interested in seeing his semblance.
That's all I can think of for now but I'm curious to see what's going to happen.