Bitcoin will have big, but i mean BIG adoption till that time and miners will be happy to mine for fees reward. Till that time USD, EUR and rest of fiat will be only numismatic assets.
We all hope that there will be mass adoption. But many people still remember the Mt Gox incident. Bitcoin would be much better off if that hadn't happened. I asked my friends recently what they knew about bitcoin, and they claimed it was a scam. I asked them why, and they told me about some exchange that ran away with alot of BTC... oh well. Mt Gox has scarred the bitcoin community.