Halo Infinite was supposed to be released by now, as the idea was to launch it together with Xbox Series S/X. But this didn't happen obviously, but as you can imagined, there are of course firm plans of what happens next at 343 Industries, and one om them includes a "new project in the Halo universe", according to a job listing:
"343 Industries is looking for a Producer to help develop a new project in the Halo universe. This is your chance to work on one of the most exciting and creative intellectual properties in the industry with one of the industry's most talented teams."
No other details are currently known, but it is unlikely this is about Halo Infinite 2 or anything like that, as Infinite has a ten year plan from 343 Industries. We would rather guess it's a spin-off of some kind, but as they are now looking for a producer, it will probably be a few years before anything is shown.