An unsubstantiated report on Dark Side of Gaming cites an industry insider that claims a Halo 5: Guardians PC port announcement could come at this year's E3 event.
With Microsoft's recent aggressive push into the PC gaming market, it seems as though the announcement of a Halo 5: Guardians PC port is just a matter of time. In fact, the latest rumor points to Halo 5: Guardians being announced for PC as soon as E3 2016 next week.
This rumor comes from an industry insider that also recently leaked the existence of an Elder Scrolls V: Skyrim remaster - a game that is apparently set for an E3 reveal as well. As is the case with the Skyrim remaster rumor, however, the claims that Halo 5: Guardians is coming to PC can't be substantiated at this time, and Microsoft has outright denied that Halo 5 is ever coming to PC, so take this information with a grain of salt.
We won't know for sure if Halo 5 is coming to PC until Microsoft comes out and says it, but a Halo 5 PC port does make sense. After all, Halo 5's Forge tools are already coming to PC, and porting it to PC would prove that Microsoft is as serious about PC gaming as it claims to be.
If Halo 5 is making the jump to PC, then it may not be discussed during Microsoft's actual press conference, but rather the PC Gaming Show conference. At last year's E3 event, Phil Spencer appeared during the inaugural PC Gaming Show to announce that major Xbox One titles Gears of War: Ultimate Edition and Killer Instinct were coming to PC, so it wouldn't be all that surprising for the Head of Xbox to do something similar with Halo 5 at E3 2016.
As for the Xbox One's other Halo game, Halo: The Master Chief Collection, making its way to PC, that seems far less likely. The same source that points to a Halo 5 PC port has said that there are no plans to bring Halo: The Master Chief Collection to PC at this time. Considering how challenging it was for 343 to fix all of The Master Chief Collection's launch issues, perhaps the company thinks it's not worth the trouble trying to port the game to a new platform.
With Microsoft bringing most of the Xbox One's exclusive games to PC, it seems likely that Halo 5 will come to the platform at some point as well. Whether or not the announcement of a Halo 5 PC port occurs at this year's E3 event remains to be seen, but if it is announced, it could indicate Microsoft's biggest attempt to woo the PC gaming crowd to date.
Halo 5: Guardians is currently available as an Xbox One exclusive, and is rumored for a PC release as well.