As the title says, it seems that there is going to be a new version of Halo Wars 1 included in the Ultimate Edition of Halo Wars 2.
Halo Wars: Definitive Edition is an enhanced version of the original Halo Wars that runs natively on Xbox One and Windows 10. Halo Wars: Definitive Edition includes improved graphics and all of the DLC created for the classic real-time strategy game.
https://store.xbox.com/en-GB/Xbox-One/Bundle/Halo-Wars-2-Ultimate-Edition/90a5bfc1-8e14-4fb6-9e9d-25c1e6edbb67?lc=1031