The question then becomes 'why would/ what would make merchants want this?'
If merchants are using btc themselves, it becomes trivial for people to want to use btc to trade with them. Are there any non shady reasons for preferring btc though? Why would you want to accept a volatile new currency when all your expenses are in a different currency?
The more I think about it the more I think that btc will need to bootstrap from some sort of tangent: goofy investment medium, payment processing technology, gray markets...
Might become the currency of the underworld.