To clarify this for modders. KSP 1.4.0 has been released as we know.... KSP 1.4.1 is a base game update that will be released simultaneously with the DLC. The DLC is an add-on that requires KSP 1.4.1. But the base game will be updated to 1.4.1 at that time. A modder should think of it like this... there's 1.4.0 this week. When the DLC releases there is an update to KSP to 1.4.1. Whether a modder's mod cares about the DLC or not... is up to them. But it will run regardless of the DL