HBO was recently acquired by AT&T in a blockbuster $85 billion deal. John Stankey is now heading up WarnerMedia and has promised to ramp up HBO's shows. This is where the opportunity to do something no one else is doing not only presents itself, but makes perfect sense; make a samurai epic. Everyone and their dog has piled onto the fantasy train after the success of Game of Thrones, which lead to the spillover piling onto the Viking theme shows. What is the only thing with global appeal missing? Feudal Japan with it's samurai, ninja, geisha, and shogun.
HBO gave us a taste of what they could do this year with Westworld setting a couple of episodes in Shogunworld, but all they really did was open the door to what's possible. HBO has the budget, they need fresh exciting content, and feudal Japan has it. Mongol invasions, the Warring States period, the battle to become shogun. There is enough content historically you could use history books to take scripts from. Oda Nobunaga, Musashi, the 47 Ronin. These are all real people who could provide seasons worth of stories.
Is there a market for it? Well, I sell a lot of samurai swords. A lot of them. I think the market for a high budget samurai epic is probably as big if not bigger than Game of Thrones. Feudal Japan was filled with backstabbing lords who demanded failure be met with death, and had no problem employing entire clans of ninja to burn down cities if they wind was blowing favorably.
So HBO, you say you are looking for content. There you go. You're welcome!