1) Windows is ending native DVD player support
Additional drivers and codecs will need to be downloaded, but Windows Media Player will no longer be able to play DVD Movies. Many media burning suites come with DVD playing software.
2) Windows Media Center is going away
Some people use Windows Media Center to watch TV on their PC or to record TV shows to watch later. You can also create a media library to share across Windows Media Center receivers (such as XBox 360). This is similar to how iTunes can work with Apple TV. However, windows is saying goodbye to Windows Media Center. It is not certain what, if anything, will take its place.
3)Windows Live Essentials becomes OneDrive Inbox
4) Windows 7 Gadgets will be removed
More information about Windows 10 can be found in this article below: