I've had too much beer but I suspect what will happen is that third party options will appear that make it possible to pay with [insert your flavour of crypto-currency here]. The reason I expect that is it would be trivial to implement some ~debit card that is either credited with money from crypto ahead of time, or a more savvy company managing the flow of different flavours at one time.. perhaps leveraging flex with something that is a BitShares DEX. I think to promote bitUSD, focus on it's primary capability.. holding the value of the dollar as digital tokens.
What is needed for big uptake, is a Government to say that such a digital token that is pegged to a currency, is appropriate and ok for businesses to accept. Any Government looking to draw wealth into the economy, should welcome the opportunity for drawing value from and digital token, having those spent locally.
I don't know what opportunities there are to engage legislators across the globe. I've done what I can for the UK call for information. Hopeful good sense will prevail over lobbyists for existing third party authorities, who might be cynical about the threat to their existing power and wealth.. perhaps this year we'll see which countries are welcome to crypto-finance... just need to be ready to adopt their currency as #1 and prompt that hard, so BitShares bit-[insert your flavour of crypto-fiat here] is the default option.