According to Renka_schedule, the manager of the japanese game schedule wiki in Japan recently tweeted that HORI will be releasing the Taiko no Tatsujin drum on 10/26 (Thursday) and can be safe to assume Taiko no Tatsujin Session de Dodon ga Don PS4 will be released on the same day. The price is set at 6,458 yen including tax.
HORIから発売される「太鼓とバチ for PlayStation4」の発売日が10月26日(木)に決定しました。価格は税込6458円。
— れんか (@Renka_schedule) July 14, 2017
The official game site has recently updated their controller page to show that the PS4 game will come standalone, as well as bundled with the controller (of course).