Do you think there is a possibility of cryptocurrencies being banned in the future for the reason of being a threat to "normal" currencies?
They are sort of already doing something to this tune
And the seizure of Btc-e exchange may be the first herald of more to come (though there can be a lot of hidden political agenda behind this attack, of course). Regarding your last question about cryptocurrencies being a threat to conventional money, this is unlikely for the simple reason that neither Bitcoin nor other cryptocurrencies are used as currencies specifically (for the most part). They are no more than speculative assets and will most certainly remain those for the time being (and likely in the future too). So they are not competitors to fiat by any means to any significant degree. But this doesn't in the least mean that governments and banks are quite happy with crypto