At the end of last month there were rumours that Yakuza 3, 4, and 5 might get remasters on the PS4, with producer Daisuke Sato saying during an interview that Sega was open for making remasters if there was enough interest from players.
It seems there has been enough interest from players, because the games are in fact getting remasters, as confirmed in the latest issue of Dengeki PlayStation (via Gematsu), which also revealed the Japanese release dates: Yakuza 3 - August 9; Yakuza 4 - Fall 2018; and Yakuza 5 - Spring 2019.
The remasters will have improved frame-rates and resolution, as you'd expect, but that's about all the details we know. Which remaster are you looking most forward to?