> in an ideal Bitcoin economy people wouldn't need to convert to USD

You're describing a situation in which the economy is split into two parts: a dollar economy and a Bitcoin economy. (I will assume that the Feds will come down hard on any "hacks" that make it easy to convert between the two without a license, like they did on offshore gambling sites and AllofMp3.) Experience proves that kind of situation just isn't tenable. Cuba and North Korea just about manage it, but only because there are lots of other barriers separating the two economies.

And anyway, we're talking about the here and now. Do you think the Bitcoin speculators and Silk Road traders are in it for the lols? Dream on.