Disclaimer
The information in the blog post is based on leaks and datamining. Knowing the developers and how they like to make last-minute changes, anything in this post is subject to change, but two out of the three banners are nearly 100% confirmed.
Upcoming banners
Three upcoming banners have been leaked and those are:

Rupee: Winter Shopper
First of all, this isn't a skin for the Rupee you know. It's a brand new character with different skills, stats, and even Burst type. For any other character like her, we will use the term alter - which means an alternative character to the base version.
While her kit was already leaked, we won't be posting it here, as we already burned ourselves too much while trusting the pre-release skills. Still, here are some pieces of information about XRupee that are unlikely to change:
Burst: Burst I
Weapon: Assault Rifle
Class: Defender
Rarity: SSR
XRupee will be added to the game with her own event Christmas-themed that will start this week on the 8th of December - its name is Miracle Snow.
We will release a separate blog post that will give our first impression of her final kit on Wednesday when the patch notes should be released. As we announced last week, we won't be reviewing or rating any new characters based on the test server anymore, and instead, a review and rating will be added within 72h of her release.
About the upcoming event, we already know the characters that will receive bonus % to drops:
Rupee: Winter Shopper - 60%
Exia - 40%
Emma - 40%
Centi - 30%
Brid - 30%
Yulha - 30%
Neve - 30%
N102 - 20%
Delta - 20%
Sadly, as you can see we're going back to only 3 SR characters that give a higher chance for the bonus drops, compared to the last event that allowed us to reach 90% easily. And yes, 3 SR - because Neve, a new SR character, was already officially announced and we will talk about her later in this blog post.
Also, here is XRupee full design:


Anne: Miracle Fairy
Similar to XRupee, this isn't a skin, but an alter - for N102 this time. Her banner should arrive 1-2 weeks after the XRupee one has started.
Also, while her kit was already leaked, we will only reveal some basic information about Anne:
Burst: Burst 2
Weapon: Rocket Launcher
Class: Supporter
Rarity: SSR
As you can see, compared to N102, her base version, she not only changed the burst type but also got an upgrade to SSR rarity. Also, both Anne and XRupee have very unique kits that force you into a specific formation to fully use their skills, and it will be really hard to play both together in the same team.
Anne will be released with the 2nd part of the Miracle Snow event which will have its own stages, rewards, and shop. This means that December will be full of goodies!
Here is Anne's full design:


Modernia
Modernia is the third leaked banner character that is slotted to be released right after the two Christmas ones. What's super important about her is that she is Pilgrim and Burst III type, so this means that Scarlet and Harran have to tremble in fear as the first Pilgrim banner is destined to have a very strong character on it. Still, Modernia's kit isn't known yet, so those are just our speculations, and she might turn out to be average.
Overall, F2P players could potentially want to skip one (or even both) Christmas characters and instead save all their Gems and Tickets for Modernia, because if she will be strong, grabbing a few copies of her will be super important. Here is her full design:

Freebie
Neve was recently confirmed by the developers in an official Tweet. While we will wait with revealing her kit until she is actually released, here are some information about her:
Burst: Burst III
Weapon: Shotgun
Class: Attacker
Rarity: SR
Neve will be a free reward from the Miracle Snow event and you will obtain 3 copies of her from various sources - so enough to MLB her.
Here is her full design:
