I thought about it and decided that bitcoin exists in the story but is like the size of gold at that point. Really big and common, but major fiat currencies still exist so far. Because the military industrial complex exists in the story, and hasn’t been de-fanged of its seigniorage yet. 

 I’m surprised that there hasn't been any substantial fiction predicting the possibilities and future applications of bitcoin. I feel it’s an incredible building block for an imagined future on which to overlay a story. Something like Iain M Banks’ The Culture.