According to a recent financial report from Sega Sammy Holdings, we might see a new Yakuza game by the end of March 2020. So, in other words, fairly quickly.
Sega didn't say anything on the matter just yet but we do know that Kazyuma Kiryu won't be a part of the new Yakuza game. Instead, we will get a new hero - Kasuga Ichiban. We also that the game will be released on PS4.
A remake of Yakuza 2 is coming to PC next month, so that will hopefully occupy our attention by the time we get an official confirmation on this matter. Fingers crossed!