Approximately at the 55 minute 56 second mark on the 343 mixer social stream 343 Industries employee Jeff Easterling (also known as GrimBrother One) stated what seems like confirmation that 343 Industries will not be chasing trends by tacking on a Battle Royal Mode in Halo: Infinite.
https://mixer.com/Halo?vod=44214540
https://mixer.com/Halo?vod=44214540