Koei Tecmo finally announced that Shin Sangoku Musou 8 (Dynasty Warriors 9) has begun development. Not much info is known currently, but here's the cliffnotes:
-Omega Force was determined to deliver something completely new for Dynasty Warriors 9, as they felt Dynasty Warriors 8 was
not a big enough step forward to warrant a numbered title (as 6 and 7 were both huge changes).
-The game has abandoned its stage-by-stage structure from previous titles, now adopting a massive open world where the entirety of Ancient China is being reproduced. Due to there being numerous mountain ranges, places where battles can occur are limited, so areas like Hulao Pass and Zhongyuan are being far more intricately designed than before.
-The nature of the open world is completely different than Omega Force's previous open world title (Toukiden 2), so the engine is being built from the ground up, rather than being carried over from the previous game.
-The combat is being completely redesigned. While they are still keeping the "one-versus-one-thousand" feel of previous entries, they wish to create something more engaging for players. Koei Tecmo confirmed on Facebook that Dynasty Warriors 6's Renbu system will
not be returning, which has relieved fans worldwide.
-All 83 playable characters from Dynasty Warriors 8: Empires will be playable in this title, as well as a handful of new characters. This includes new character Zhou Cang, who is meant to be a more comedic character that is being designed specifically for players to have fast, frantic fun. Zhou Cang will be first appearing, however, in the spin-off title Musou Stars. New characters from the recent Dynasty Warriors: Godseekers (Shin Sangoku Musou: Eiketsuden), namely Lei Bin and Lixia, will not be playable.
-No release date has been announced. The only confirmed platform is PS4, and if I had to guess, late 2017 at the very earliest.

Zhou Cang, as he appears in Musou Stars. This appearance will more than likely carry over to Dynasty Warriors 9.
Zhou Cang's Musou Stars gameplay teaser.