The roadmap was summarised nicely by Tim already and you can check his video here. Below you will find a short summary of what's coming next month.
New characters
Kagura

Kagura is a healer and buffer who can give her party ATK and Lifesteal buffs, but also Barrier them. She's mostly a PVE hero who shines in Raids but also was pretty popular in PVP back in CN and JPN, but in the Global region, we think she won't be that good (mainly because of Madoka collab and Alma coming the same month).
Condor

Condor is a damage dealer who focuses on debuffing enemies. Similar to Kagura, she's mostly a PVE hero.
Alma

Alma is a healer that can resurrect the whole team at once. Yes, you read it right - the whole team. She's really strong in both PVE and PVP.
Yuui

Yuui is an attacker who can abuse enemies that buff their allies by attacking them right after they use their spell. She was a meta unit in CN and JPN for a very long time and she stopped the Alice/Timmy meta. Still, we already have Madoka collab in Global and Homura does a similar job as her.
Who should you pull from those 4?
Our suggestion is to skip all of them if you're a F2P player. Mainly because there's a high chance we will get Frame Arms Girl collab in November together with Clarice banner (she's Alice on steroids - the only SSS unit in PVP and PVE).
If you really want to pull someone then get Alma as her AOE resurrection is something really unique.
Rerun characters
Both Shura and Cream events will be rerun this month and they will come with their banners. If you missed Chihaya, you can get her for free from the Shura event.
Union Pass
Kagura's skin will be the next Union Pass skin:

New Unique Equipment
Two units will receive their UE this month:
Michelle
Cream
Other updates
Dark Zone level 7