The idea of paper money being banned is ludicrous, I mean maybe in the distant future sure but I haven't seen any proposals whatsoever for how a digital currency could ever work in an offline setting. Paper money works whether an internet or phone connection is available and even when there is no electricity. If we had a bitcoin based digital currency what will happen when the internet goes down, will transactions be unavailable until it is working again?

Think about disaster hit areas, without paper money transactions would be impossible in all but an old fashioned barter setting.