USD is the reserve currency of the world.
Makes sense to assume one is talking about it when using the term "fiat".
All the fiat currencies are racing to the bottom together in this "currency war".
So it makes sense to throw them all in one bucket. It's all basically the same crap, just different color paper.
The current deflationary scare and subsequent rise in fiat value compared to all asset classes is temporary. The central banks cannot taper without too much pain.
There will be some sort of currency reform, I'm pretty sure.