Board Thread:Questions and Answers/@comment-24751993-20150411115132/@comment-26501002-20150411162722

It is possible that the devs didn't "secretly" add them, but rather added files to the package to use later. With the way update patterns seem to be for PE, I think the next major update in which the Nether - and maybe even the End - are added will be 1.0.0.