China-based developer MiHoYo, it seems already has a new game trademark, Honkai Impact 4, as shown by Twitter user Daniel Ahmad. In addition, miHoYo is also developing Genshin Impact, which is scheduled to begin the final beta version next month, July 2020.
Previously, Honkai Impact 3 was a sequel to the third Honkai series. This game was first released in China on October 14th 2016, so it has been four years from now, which is quite a long time for mobile game titles that still exist today. Honkai Gakuen, as its predecessor, was released in 2014, which means there is a 2-year gap between Honkai Impact 3 and Gakuen. And now four years have passed, it seems like a decent time to make a new title.
Maybe some players think that miHoyo will release Honkai Impact 4 for several platforms at the same time as they did with Genshin Impact. Honkai Impact 3 also has a PC client, while Genshin Impact will be released for Playstation 4, Nintendo Switch, and mobile.
Honkai Impact 3 players must be impatient to find out more detailed information about Honkai Impact 4. So we just wait until this is revealed.