Disabling fontawesome in CB disables loading of our CSS file. It's not going to remove all the icon classes.
Is there an easy way to upgrade all CB icons to version 5 or 6 ? (we have a fontawesome pro subscription)
Turn off CBs fontawesome then load in your own with the migration JS file so it migrates the fontawesome 4 classes for you. That's the best I can suggest.
We do not plan to move to 5 or 6. They've gone way to commercial with it. We'll be switching to a more open source solution with CB 3.x that will use a class mapper configuration file so you'll be able to replace all icons with whatever solution you like if CB 3.x solution isn't to your liking.