People were asking if we would get a "beta" of the shadows and shaders. Like you quoted - but there is more to it somewhere in the topic - he said that we will get an early version of it, just so we can test it. Then afterwards, when everything has been fixed and optimized, we will get the complete shadows and shaders.
So I'm guessing the test version will just be a v20 release, with them off by default. But then v21 will be the full release, with them on by default.