Why wouldn't it? I mean, what is wrong with that. You are one of the users on here that complained that SEGA didn't dub Yakuza (a game about Japanese culture) into English. We have not seen anything about the squads speaking in Japanese, maybe the narrator only talks in Japanese for the trailers, like in the Yakuza English trailers. We don't know yet.
If you want to be legit, the English version should be Japanese only, since the game takes place in Japan.