Over this past weekend, a small change was made to the UK and US Amazon store pages for Halo 5, which at first glance looks pretty inconsequential, but might ultimately reveal that the game is soon be ported to PC.
— AllGamesDelta (@AllGamesDelta_) September 9, 2018
When Halo 5 originally released on Xbox One back in 2015, it released with a banner at the top of the box proudly stating "Only On Xbox One". However, the box art on Amazon was updated over the weekend, and the new version now says "Xbox One Console Exclusive". Based on Microsoft's E3 presentations of the past few years, we know this wording means it's on Xbox One as well as PC, rather than just being on Xbox One.
While no port has been announced, we're now expecting to see an announcement sooner rather than later.