Halo's Franchise Developer, Frank O'Conor, has recently denied the existence of an upcoming Halo Infinite Battle Royale mode, though the possibility of something analogous hasn't been written off completely. This was in response to a report that ran contradictory to what 343 Industries has said in the past about available game modes for the latest in the Halo series.
Not a lot is currently known about the launch content of Halo Infinite aside from the fact that it's going to have splitscreen co-op, increased support for the Windows launch, and callbacks to Halo Reach in terms of customization. However, O'Conor's comments make us pretty confident that a Halo Infinite Battle Royale mode isn't going to be part of a Day One patch for the game.
It's been reported by Comicbook that when O'Conor recently discussed the content that would be available for the latest installment in the Halo franchise, a Halo Infinite Battle Royale mode was distinctly off the table. The insinuation appeared to be that while such a game mode wouldn't be a priority for the studio, players may well be able to make their own using the Forge and its extensive map creation tools. While it may not currently be a priority for 343 Industries to work on a separate mode that apes the likes of Fortnite and PlayerUnknown's BATTLEGROUNDS, it was still noted as a "gameplay possibility" when O'Conor was discussing the franchise as a whole. He was also quoted as saying:
"The launch modes for MP are not 100% defined and are subject to change till quite late in the process - but Battle Rifle will still be there. So you can have BR. But are we interested in big social modes with loads of organic shenanigans? Yes. Specifically a blimp full of survivors heading to an island after a (metaphorical) lecture from Beat Takeshi? No."
From what we can gather about O'Conor's comments, a Halo Infinite Battle Royale definitely doesn't sound like it's going to be available on launch. However, there might be some intriguing subtext around his note that a Battle Royale mode could "be made for any of the Halo games" in the Master Chief Collection. This could mean that we potentially see a Battle Royale mode in another Halo title, or that this fated mode could potentially show up in Halo Infinite further down the line as a rotating game mode since implementation as a primary option seems unlikely at this point.
Alternatively, it could just be a way of 343 Industries hinting that it's trying to keep its options open when it comes to the overall direction of the franchise. In either regard, the open-ended nature of O'Conor's statement leaves a lot for fans to speculate about in the coming months until Halo Infinite.