Arcade mode doesnt even use the proper character select screen apparently, someone also stated ranked probably will use the same layout as the beta, and probably wont use CAS. So from there i'm starting to wonder what modes do actually use the actual character select, and where we can use CAS. Nothing has actually been proven as far as online is concerned.
And to add to this im starting to get a bit skeptical abiut this "CAS share" feature because if they did in fact cut all forms of online customization, i could see them using this as the means of online cuatomization in a sort of apologetic bone being thrown if that makes sense.