On the point of Japanese sales - Sega have been branching out to Asia for years to expand game sales, and its working. Yakuza 6 has sold almost a million units as reported a month or two back. So overseas sales in Asia and heightened interest America etc. has helped make up the deficit of sales lost from the Japanese audience. We already know the games will continue to build on Sega's Dragon engine that Kiwami 2 and 6 run on, and that Shin RGG with Ichiban is the next mainline game coming. The Dragon Engine is still being optimised for the base PS4 console (Yakuza 6 had screen tearing issues, Kiwami 2 does not and has better loading etc.) but even then I don't see the engine running on the Switch. Since part of the time and a big part of 6's cost was ,most ;likely spent on rebuilding the engine (with the rest going to Takeshi Kitano to appear in the game ;) ), I don't personally see Sega jumping ship to a different, more Switch friendly engine just yet. I see the 0 and Kiwami PC tests being more important, and think by the end of the year most of the series will probably be on the PC as well as the English remasters on the PS4.
As for the Switch? Sega definitely shouldn't sleep on that opportunity, but I don't think doing ports is the best idea, especially seeing the Wii U ones bomb so much. I've personally thought for a while that they should develop a separate Yakuza series (with different protagonist(s)) for the Switch's market base. Sorta like how the PSP got the two Black Panther Yakuza games. Probably use a hybrid of the older Yakuza 5 engine and go from there. Pitched right I think it could do really well in Japan at least, and I do really want another portable Yakuza game if for nothing else, just to get all that awesome side content on the go.
