Danganronpa is a very popular series of murder mystery games with a very passionate fanbase all around the world. With the first game in the series, Danganronpa: Trigger Happy Havoc, being first released in 2010, this year marks the series' 10th anniversary.
There have already been multiple things relating to the Danganronpa series released this year to celebrate this milestone, including mobile ports of the first two games and special skins for Identity V. However, information involving any new game or anime has been quiet.
It wouldn't be out of the question for something new to be announced before 2020 ends. While Danganronpa V3: Killing Harmony marked a definite end for many aspects of the series, there could still be another potential killing game or spin-off title in the future. However, with any future Danganronpa games, there always has to be some kind of mastermind. The following characters from previous games could potentially return as a mastermind of some kind. Spoilers for all of the games and anime will be discussed.
Sonia Nevermind
Sonia Nevermind is the Ultimate Princess and one of the survivors of Super Danganronpa 2: Goodbye Despair. At the end of the game, it is revealed that Sonia and the rest of her classmates present at the Killing School Trip were brainwashed into a terrorist group under Junko Enoshima known as the Ultimate Despair. While Sonia and her classmates were brainwashed, the group had committed various atrocities across the world in the name of spreading despair.
In Sonia's case, she caused her entire home country to be destroyed in the name of despair. She was eventually however found by the Future Foundation and put into the Neo World Program in order to undo her brainwashing.
There is potential for another killing game-styled Danganronpa game to be released during Sonia's time acting as the Ultimate Despair. In it, the characters could all be people from Sonia's home country or people brought from outside of the country meant to put all of Novoselic into despair before it is destroyed. Sonia could be also trying to copy Junko's killing game from Danganronpa: Trigger Happy Havoc in her own country.
Unlike most other masterminds, however, Sonia wouldn't be able to be killed at the end due to her role in both Super Danganronpa 2: Goodbye Despair and the Danganronpa 3 anime. The game would likely end with Sonia's capture by the Future Foundation.
Monaca Towa
Monaca Towa was the main villain of Danganronpa Another Episode: Ultra Despair Girls. In it, she used her influence and technology to brainwash all of the children of Towa City into killing every adult in sight. This was all meant to break Komaru Naegi and turn her into the next Junko Enoshima so Monaca could get back at Makoto Naegi for causing Junko's death. While Monaca's plan failed, Nagito Komaeda helped Monaca become the next Junko Enoshima herself.
While Monaca continued to cause problems in the Danganronpa 3 anime, her arc ultimately ended with her getting bored of the events happening and just leaving Earth to play video games in space. This was the last update fans had on her character at all making a lot of the build up feel wasted by the end of the Hope's Peak arc of Danganronpa.
There is always a possibility for Monaca to return in the future as a teenager or adult as a surprise mastermind in a future game. Although the world began to properly rebuild after the events of Danganronpa 3, Monaca's return could potentially start a new killing game in a secret location to taunt Makoto and the Future Foundation. This killing game could also have older versions of the warriors of hope return with one of them even possibly being the main protagonist.
Shuichi Saihara
Danganronpa V3: Killing Harmony is one of the most polarizing entries in the Danganronpa series due to its ending twist as well as the various harsh jabs toward the Danganronpa fanbase for wanting another game in the first place. Out of all the main entries in the series, Danganronpa V3: Killing Harmony has the lowest survivor count with only three people surviving at the end. One of these survivors is the game's main protagonist, Shuichi Saihara.
The end of the game reveals that every character in the game isn't real and that their memories and personalities were pre-written characters that were inserted into their brains. It is also revealed that the version of Danganronpa that everyone was participating in was a television show that everyone willingly signed up for. The game ends with everyone refusing to cooperate and gets the show cancelled.
It is unknown what happened to the survivors after the school is destroyed, but it would be very likely that the creators of the Danganronpa show wouldn't be happy with the actions the survivors took. While the Shuichi Saihara that escaped the academy likely wouldn't be a mastermind of a Danganronpa game, the original personality of Shuichi has the potential to become dangerous.
If the fictional version of Team Danganronpa inside V3's universe still has Shuichi's memories stored somewhere, they could reasonably make Shuichi have to go up against who he originally was. According to the audition tape, Shuichi wanted to be an Ultimate Detective on the show because there hadn't been a murderer in Danganronpa who had also been a detective. This implies that this Shuichi would not be happy with the way his character went in V3 proper and could be used against the survivors for retaliating.
Junko Enoshima
Despite dying in the first game, Junko Enoshima always somehow is the mastermind of the Danganronpa games in some capacity. Sometimes she's directly in charge like in the first game and in Danganronpa 3: Despair Side, but other times its an AI version of her like in Super Danganronpa 2: Goodbye Despair and Danganronpa Another Episode: Ultra Despair Girls. Because of this, it is to be expected that Junko can never be truly avoided.
While Danganronpa V3: Killing Harmony played with the idea of Junko being behind everything with the mastermind really being someone cosplaying as Junko, her influence on Danganronpa will likely never leave. It should be generally expected to see her if any other Danganronpa titles were to come in the future.
A new Danganronpa game has not been officially announced.