it is very difficult to say something about the timing. certainly the future in which bitcoin (or altcoin) replaces paper money seems tempting. However, most governments are cautious about the crypto market.
Yes, the government must be alert to the presence of crypto, of course the government can not stop cryptocurrency if one day marketcap has reached millions of dollars, and I am sure that someday this will happen so that we must be ready to face this reality.
Nothing is impossible, but ban cryptocurrency, it won't help the government earn many money through this field like now. Why do I say that? Because the government are also putting money to buy Bitcoin and cryptocurrency. Recently, a confession from a senior Korean official indicates that it is true.