As someone who owns all of them, this is a really scummy way to handle the Fireteam DLC. At no point was it ever made clear that these were ever “limited time” DLC, and they were just suddenly removed the day the new version dropped without any warning.
Considering just how little content there is for Fireteam, permanently locking new players out of any new stuff (and not just the new character models, but new additional weapons as well) is absurd.
Really hope the Fireteam DLCs come back at some point. Hopefully sooner rather than later.