I don't have a date for that. I first want to finish Ancient Warfare 2. I don't mean end the development, I want to bring it to a state, which could be the end of development.
The game will reach this state in about 1-2 months(2-3 updates). Then I will start to create the modern spin off.
About the spin off:
I will use the custom battle editor and the level bundles. All other gamemodes will be removed and the content will be replaced with modern stuff from WWI, WWII, modern and maybe future content.
Of course, I will make adjustments to the AI and other systems.