No doubt.....at the end of Shenmmue II he threw the dagger at the map hitting Guilin.....it's pretty clear Ren will be on his way.
I can bet you will see many familiar faces in Shenmue III.
just by his statement of "woohoo. Did you hear that!? Treasures! i told you my hunches are always right..." etc. he has to come to help Ryo since he has become a full friend, and his greed