From the Attack On Titan Wiki’s translation of an interview with author Hajime Isayama in the August 2016 issue of Japanese magazine Gong Kakutogi.
Isayama: Tankobon Volume 20 will be released on August 9th, and it will approach the climax of the story.
Released in Japan August 9th, volume 20 with chapters 79-82 will feature plenty of this, along with an epilogue that sets the stage for the series’ climax.