The countdown has ended and Falcom has finally announced The Legend of Heroes: Trails of Cold Steel IV -The End of Saga-. As the title suggests, this will be the final game in the Cold Steel spinoff series.
"With The Great Twilight set into motion, a 'curse' has spread across the entire empire. The 'Ashen Knight' Rean Schwarzer lost himself to his ogre power that went out of control. As the world approaches its end, what will the remaining members of the new and old Class VII do?" said Falcom's press release (translation via Siliconera).
Trails of Cold Steel IV is scheduled to release on PlayStation 4 in Fall 2018. That's the Japanese release of course and there's no indication of the game coming to other platforms.