The series looks like it'll get quite close.
If RGG 3 ends up being Yakuza 1/2, plus Kenzan camera, the third game could end up being a more action packed Shenmue.
I don't know what makes Yakuza remind me of Shenmue. Maybe it's the fact that it's set in Japan? The atmosphere? The 'separate' battle sequences? There are plenty of third-person games set in modern day, but none of them remind me of Shenmue -- Even Bully, which some people here think is similar.