I know HALO 5 is nowhere near the most well liked game in the series but I just feel like making it available on PC via the MCC or otherwise would round things out nicely before Infinite drops.
There are currently no plans to bring Halo 5 to PC, feel free to use the existing topic for this
https://www.halowaypoint.com/en-us/forums/6e35355aecdf4fd0acdaee3cc4156fd4/topics/halo-5-on-pc/525dadaf-2c2b-4626-8c48-c7c83e150d46/posts