Together with Windows 8, Microsoft introduced the Metro design, a modern and clean design language. With Windows 10, Microsoft made several adjustments to this design which is now called “Microsoft Design Language 2”.
According to WindowsCentral, Microsoft is now working on a new much more streamlined design language for Redstone 3, codenamed Project NEON.
Project NEON will not replace the current design entirely but will build upon it. The new design will add more flair to the current Windows 10 design and come with more animations and transitions. The design is described as “Very fluid, lots of motion and nice transitions.” Some more information about Project NEON reveal that it will connect the holographic and augmented reality with the desktop environment.
The new design language appears to be part of Redstone 3 which will be released in Fall 2017. Insiders will probably see the new design earlier because the first RS3 builds will start rolling out in April-May 2017. Microsoft might also talk about Project NEON and the new design language at BUILD 2017.
Personally, I like the current Windows 10 design. Nevertheless, next year in fall the current design will be more than 2 years old so it would be time for some design changes.