I really don't know how well the story of Chushingura will translate. It illustrates one particular nuance of "Bushido Spirit" sitting in the niche between the ideals of "Hagakure" and those of "The Life Giving Sword". I doubt it would respond well to the "Hollywood treatment" and I doubt Keanu Reeves has the subtlety in his acting to pull it off. Not enough action to be a proper action film and has that typically japanese 2 hours of plot setting for 10 minutes of intense action at the end.
It may be a good film, possibly spoiled by any references as to its origins, rather like the remake of "The Italian Job". Compare Besson's "La Femme Nikita" with the Bridget Fonda remake "The Assassin" then multiply the bits "lost in translation" a hundredfold. Chushingura isn't a story you can remove from it's context, like transplanting Julius Caesar into a modern fascist state, nor is it a story you can pastiche like "Wild, Wild West" or "Starsky & Hutch".
I dunno, I'll definitely look out for it, to see how it'll be "treated", but I'm not expecting to be anything but disappointed. Which will be a very pleasant surprise if I'm proved wrong.