Both Xbox One and Windows 10 users will be able to download the remastered version for free.

The official information comes from a good source:

Aaron Greenberg is the Head of Xbox Games marketing at Microsoft. Phantom Dust was announced as a reboot of the IP, but instead the developers brought back the original code and made it well-suited for the current-gen platforms.

Both Windows 10 and Xbox One gamers will be able to add the game to the library for free. The original isn’t needed in this case.