During a 2013 Nintendo Direct, the late Satoru Iwata and Sega's chief creative officer Toshihiro Nagoshi announced that HD remasters of the first two Yakuza games would be coming to Wii U in Japan only, which was the first and last time the series has ever released on a Nintendo console. Like most third party Wii U games, the HD update failed miserably, and it has seemingly made Sega gun-shy about Nintendo consoles in general.

In an interview with French site Gameblog, Yakuza producer Daisuke Sato was asked about whether the Switch would be a good fit for Yakuza titles, as games like Yakuza 0 and Kiwami were made for PlayStation 3 originally and should run fine on Switch. Unfortunately, Sato suggests that the Wii U releases are the reason the Switch won't be getting any Yakuza games.

In a quote translated by NintendoEverything, Sato said “To be realistic towards what happened, Yakuza 1 & 2 for Wii U was a significant failure. But our goal is still to develop cross-platform as much as possible, and we know that it brings an extra audience, that it allows us to attract more people. That being said, when it comes to Switch, I am convinced that it would not be the ideal platform on which to develop Yakuza games. Maybe the public is not expecting that kind of game on Switch. They may be used to different games. It may not be the ideal platform. Regarding Xbox One, we could consider it, knowing that Xbox One users might be more likely to be interested in a game like Yakuza. That could be an option.”

Nagoshi did show up on stage during Nintendo's Switch reveal in January 2017, but it seems that he was there to represent Sega as a whole's support for the system rather than indicate any chance of Yakuza coming to the Switch. Other Sega support for Switch includes Sonic Forces, Sonic Mania, Valkyria Chronicles, and more.

Meanwhile, Yakuza 0's PC port is releasing on August 1, while Yakuza Kiwami 2 is releasing on PlayStation 4 on August 28.

[Source: Gameblog via NintendoEverything]

I don't think Sato is necessarily wrong from a market perspective, even if his reasons might be. Porting the series to Switch realistically means 0, Kiwami, and the ports of Yakuza 3, 4, and 5. Yakuza 6, Kiwami 2, and any other games on the Dragon Engine likely wouldn't run on the Switch, so you're basically only expanding the audience to people who have never played those games and wants to play them on a portable. That said, nearly everything failed on the Wii U, so using that as reasoning feels shortsighted.