Before Bungie became known for Halo and Destiny, it launched a critically and commercially successful game for the Apple MacOS, Marathon, in 1994. Marathon later got two sequels in 1995 (Marathon 2: Durandal) and 1996 (Marathon Infinity). Due to its success, Microsoft tapped Bungie to work on Halo for its then-new gaming console, Xbox. Now that Bungie is a part of the Sony umbrella and has expanded many times over the years, it has all of the resources to work on multiple projects at the same time.
If we believe the rumors, one of Bungie's upcoming projects is a reboot of the sci-fi shooter series.
According to Insider Gaming, Bungie's Marathon reboot is already in a pre-alpha state and will turn the seminal shooter franchise into a squad-based, team-extraction-type multiplayer title. Jeff Grubb later corroborated the rumors, adding details that the game is a "free-to-play live service title" with "highly customizable" characters and is an "authentic Bungie FPS experience."
With both Grubb and Henderson reporting the same thing, an official announcement is all a matter of when and not if.