A new Yakuza game is in the works, and it is set to take place after the events of Yakuza 6. This new game will feature a new protagonist, 40 year old Kasuga Ichiban. We've already got a new look at this new hero in 2017:

New Yakuza Hero Announcement Trailer

We also have some background info on the new protagonist, courtesy of Dual Shockers:

That man is Kasuga Ichiban, former lieutenant of the Arakawa family of the Toko Clan. He never knew his parents, and joined the Arakawa family to follow a man who saved him when he was adolescent. In 2001, he took responsibility for a crime committed by the young head of the family, and spent seventeen years in prison. Yet, when he returned in 2018, he found a changed city, his old companions disgraced, and an unbelievable betrayal. 

There was also a prologue released all the way back in 2017:

『新・龍が如く』プロローグムービー

Series producer Daisuke Sato confirmed in a recent interview that more info on the new game will come on July 10th:

“At this time, that is not a question I can answer. On July 10, we will announce the supporting actress for the new title, as well as share the latest information on the new title, so please look forward to it.”