If we have a problem (we have) with somebody sending assets to exchange addresses on wrong chain. What if exchanges used their own ss58 which would be saved on known exchanges list and we would know on the UI that you are sending to wrong address? This would require literally 0 change other than a json and harder part → convincing exchanges to display deposit addresses differently.
We could then unify all the addresses per consensus or whatever we want. ( Or everybody changes this and we keep exchanges to use polkadot prefix =) )