I think most people generally think 1.0 = release, no longer beta, expected to not have bugs and all core functionality is there, anything added after that should just be expansion content or unexpected bugfixes.Just for clarification: There are many different kinds of counting.
Many devs count like 0.9 - 1.0 - 1.1 - 1.2 - ...
Until May he wrote that possibly one main road will be finished, but not the final game.
Its open how the final version is called.
But aside from that, the dev blatantly said his motivation for that is he wants to start another game and we all know from experience what that means.