I am going to post a schizo theory here.

Ever since the BRS patch, Kuro has been releasing characters in a certain pattern. If you align all the A-rank characters as the starting point, you’ll notice two distinct patterns, Pattern A and Pattern B.
>Pattern A consists of 2 Free and 3 Limited characters,
>Pattern B consists of 2 Free and 2 Limited characters.
From this, we can roughly estimate how the next five characters will be released.

Each pattern always ends with a very popular character. The most likely candidate is someone like Karenina or Kuro might throw a curveball and release Vonnegut to get the players hyped. Which character do you think is most likely to fill the last spot?