The first improvement (Media Foundation by FFMPEG) could be significant. Currently, VALVe generates large shaders to re-render those Media Foundation videos into other free codecs. These shaders can be several gigabytes in size for some games with lengthy videos. With FFMPEG, those videos could be played without being re-encoded as shaders.
Good information here about EXO, and ChromeOS:
I don’t even knowed that Chrome OS is/will be replaced by Android as an overlay.