In my humble opinion, that might overcomplicate things without providing much in the way of risk reduction. Owning a basket of currencies might make sense in a world where, globally, only some central banks had loose money policies. But, at least right now, central banks are all printing money. If you’re a US investor like me, you might have inflation concerns, but if inflation occurs globally, I might do worse owning a basket of currencies than owning USD.

What would I do if I were concerned about inflation but wanted cash? I suppose this doesn’t help anyone who’s solely into indexing, and I know this locks up cash, but I’d look for unlikely-to-fail dividend-paying companies that are relatively protected against inflation and that are trading at relatively fair values. Essentially, you’d be saying “I don’t care if I can’t sell this stock for 10 years so long as the 4%+ current dividend yield ratchets up at or above inflation.”