Sega revealed at the PC Gaming Show in June that Yakuza 0 and Yakuza Kiwami were being developed for PC, the first games in the series to come to the platform. But possibly not the last: Sega's first quarter appendix for its previous fiscal year indicates that Yakuza 6: The Song of Life, which was released worldwide on the PlayStation 4 in April, is headed to the PC.
It could be a mistake, as the listing indicates an April 2018 release date for both the PS4 and PC versions of the game. But with Yakuza 0 out today, and Kiwami expected later this year, it's reasonable to think that other games in the series will come our way too. I've emailed Sega to ask if Yakuza 6 will actually be one of them, and will update if I receive a reply.