The new DLC is called "TRS21 - Beloreck - South Ural Mountains". So the next game version will be TRS21? Nothing about this in last Trainzletter (received today).
Welp... now I definitely hope this route will be available for purchase in TRS19. Honestly, I'd rather pay $39.99 and have the route permanently than pay for Trainz+ each time I suddenly feel like I want to use it.