It all depends on what their benchmark for success is for the series in the West. It's not as if Sega pressed two million copies of Yakuza 4 and only sold 200k. They knew in advance that sales would be in that range, and budgeted accordingly.
I meant on expanding the audience really.
The original sold 75,000 in America, Yakuza 2 sold 25,000, whilst both Yakuza 3 and 4 both did 50,000 (So much for that supposed backlash) and Dead Souls sold way less than 10,000 on its debut month.
So SEGA had all these chances to try and significantly grow the fanbase and it never materialised. Issue with marketing, a bit with the games themselves, and the fact it was a Playstation 3 exclusive, but I do not see the Western sales ever increasing much unless they flat out reboot the series and vastly change the gameplay.
Whilst being a major publisher, whatever profits Yakuza's Western sales brought in are far too small for them to continue supporting the franchise here. For reference, Hatsune Miku is expected to sell 150,000 units in America alone and that title is always portrayed as some super niche title (Not that I agree with that sentiment)