Unless the gas station and grocery store next to their house accepts BTC, they will still be converting to fiat. If BTC debit cards pop up that are widely accepted, the guy might not convert to fiat and just spend BTC for gas, but then the gas station owner would convert it to fiat? lol. How exactly do you solve the "prevent BTC from being converted to fiat" problem?
As long as the dollar exists and doesn't lose over 1% of it's value in a week, people are going to be converting to fiat over BTC because they don't feel like staring at their computer monitors with the finger on the sell button all day. You really need wild swings in fiat value for BTC to make that leap of not being instantly converted to something more stable. But this goes right back to square one of people that believe BTC will either be worth a lot or nothing depending on what happens with government mandated currency.