Rumors that Halo 5: Guardians is coming to PC surfaced when Amazon posted box art of the game that changed the "Xbox One Exclusive" tag to "Xbox One Console Exclusive." However, Microsoft has since reaffirmed that Halo 5 is not coming to PC.
A Microsoft spokesperson told CNET, "As we've shared previously, we do not have plans to launch Halo 5: Guardians on Windows 10 PC." Halo: Infinite is still scheduled for PC at least, but Microsoft hasn't confirmed whether Halo's sixth mainline game will be a part of the company's Xbox Play Anywhere program so it's unclear whether players will have to buy the game twice to play it on both console and PC. Halo: Infinite will be the first game from the main Halo series to release on PC since 2007's Halo 2.
Last April, Xbox head Phil Spencer told players they should look forward to "an official classic Halo experience making its way to PC," but there has been no follow-up from Spencer or Microsoft as to what that might be. With no plans to release Halo 5 on PC, the next logical assumption is Halo: The Master Chief Collection--which was recently added to Xbox Game Pass.
Halo: Infinite is coming to Xbox One and PC. Microsoft hasn't revealed a release date yet, but the game is a part of Xbox Game Pass so subscribers will get it for free. Microsoft has also confirmed that the game probably won't have a battle royale mode.