*** YES *** We are doing a File Manager for WP8.1! I know a LOT of you are looking for this (thanks for the tweets, I’ve read them all). In fact, I’ve been running a build of it on two of my phones for the last week or so and it’s getting to pretty good shape.
He then went on to tease a series of screenshots of the new feature. Expectedly, the app allows users to create new folders, search for files, and move stuff from the onboard storage to an SD card. According to Belfiore, File Manager should be ready before the end of May. That said, it's not as if current users don't have other options to turn to. In the Windows Phone Store, there are already several file manager apps, including the popular (and our personal favorite) Pocket File Manager that costs US$1.99.
Of course, there were many more other things discussed during the Reddit AMA session. Windows Phone Central has rounded up some of the highlights, including a coy answer to the question on whether Cortana would come to PCs, so be sure to check it out.