Some rumors simply insist upon themselves and show up every year ahead of major events, whether or not this adds to their validity is unknown. Perhaps if it's rumored for long enough, it will eventually become real. Xbox exclusives Halo: The Master Chief Collection and Sunset Overdrive seem to be stuck in this cycle.
Last year, both games were rumored to be heading to the PC via Windows 10 prior to Gamescom 2015. At the time, the leaker was known for having leaked Halo 4 footage prior to its release, so the rumor came with some credibility.
Once again, Halo MCC and Sunset Overdrive have been rumored for PC. NeoGaf user Enter the Dragon Punch (via RectifyGaming) stated the rumor mattor of factly in response to someone questioning which games to purchase for the Xbox One, if any:
"Sunset Overdrive is coming to PC, so whatever. Keep it for Master Chief Collection, otherwise sell it."
Enter the Dragon Punch is also the one behind a recent surge in rumors on which games Bethesda is bringing to E3. Either this individual is an industry insider or he's throwing tons of rumors at the wall and hoping some stick.
There's some credence to this rumor, though. Microsoft is making a huge push towards unifying the PC and Xbox console and recent rumors suggest that the Xbox UI will be heading to Windows 10.