It was posted by Activision in a blog post but got deleted so i'll post a link in the OP.

To replace supply drops a new challenge teir system. Similar to Fortnite there will be different teirs with cosmetics, guns, and emotes and this si going to be free for everybody in BO4. You will be able to move up the tiers by completing challenges but you can spend your CoD points to unlock teirs and get what you want instead of spending money on supply drops and hoping you get what you want.