Sega has revealed new information about Yakuza Kiwami at TGS 2015. The release date has been announced to be January 21, 2016, on PS4 and PS3.
In addition, Sega also revealed Yakuza 6. Not much information is available, but we do know that it will release on PS4 in fall 2016, and that a limited playable demo will be included with Yakuza Kiwami.
No word has been given on a western release date for either game.