It’s been over three years since the release of Samurai Warriors 4 back in September 2014 in Japan and Koei Tecmo president and series producer Hisashi Koinuma shared an update on the series’ official Twitter account.
— 「戦国無双」公式 (@sengoku_musou) November 10, 2017
[Producer Koinuma] It’s been a while. [Work on] the next title has just begun, so please look forward to the Musou series’ latest title Dynasty Warriors 9 for now. As for what comes after Samurai Warriors 4, it’ll end up taking longer than the 4-year interval of the Olympics, but we’re putting some thought into it. Thank you for your continued support of the Samurai Warriors series.
We’ll do our best.
So basically this confirms that work on the next Samurai Warriors has begun, but Koinuma-san doesn’t specify if it’s Samurai Warriors 5 or something else. He says that the interval from Samurai Warriors 4 to the next title will be longer than the 4-years we see from the Olympics, so we’re guessing he’s talking about Samurai Warriors 5 as the series’ latest entry was a spin-off title Samurai Warriors: Spirit of Sanada that released in Japan back in November 2016.