Not according to the showmakers:
Justin Marks: There’s a little ambiguity that we’d like to stay there. But definitively, after the shock of Mariko’s death, we initially frame the story as if it were the recollection of an old man looking back on his life with regret in some way, only to find that what we were really seeing was the dream of a young man looking forward with regret to the life that he could possibly have. We really wanted Blackthorne’s choice at the end of this show, from the very beginning, to be about a denial of this path. To turn towards a new identity, a new life. There’s a very famous portion of the book where
Blackthorne proposes seppuku, and that’s a moment that carries a lot of weight. But it occurs earlier in the book, and we didn’t feel like it was earned, so we kicked it down the line to where it carried more weight. That began to be the Rosetta stone that allowed us to open up Blackthorne throughout the season.
Toranaga and Blackthorne turn toward a new life—and a new world.
slate.com