Only the Author knows when the 1.0 Version comes out and even than there's no reason why he shouldn't continue the game after the 1.0 Version. However generally speaking after V 0.9 there's no reason WHY 1.0 should be the follow up version, it could literally continue with 0.10 insteadIs the game going to finish in 2 updates at 1.0 or is it going to go on for longer?
And not even that's guranteed since most people would version something as 0.0.1 as the first version or use Alpha and Beta to further differentiate, the point being there's no real binding rule to it other than "the higher the number the newer the version"