It's a good alternative. Dollar will always stay. I hope Bitcoin will come even good known as the dollar and the euro. If everybody found his way to the BTC, the future looks good.
Maybe for the next few decades Fiat currencies will stay intact, but in future it will be cryptocurrencies .I don't know will it be bitcoin or not, but cryptocurrency is the future.
Lol;) what if some government creates or adopts some other cryptocurrency?