CB is absolutely the biggest concern right now. And that alone could dictate our ability to get past the group stage.
But The USMNT was far healthier during qualifiers than it is now. A lot of players on the roster are coming back from injuries and while they will have been cleared to play for they wouldn't be on the roster, that's not the same as them being 100%.
So while we can all hope for the best, health-wise, for those players on the roster, I've personally adjusted my expectations downward from where they were at the end of qualifying.