According to the source, Microsoft will supplement the Windows 10 toolkit with a small application called Video GIF Capture, which will allow you to record video of the interface and save it in GIF format. The OS has the ability to do this using the Xbox Game Bar utility, but it does not support GIF.
A separate utility will appear as part of the PowerToys update, it will allow you to save screen captures to GIF, but will not be able to convert video files to GIF. But you can cut pieces of video and save files with different quality settings. The utility will allow you to save what is happening in the active window in GIF or select an arbitrary part of the Windows interface for capture.