Physical dollars are an important medium of global liquidity. Taking them out of circulation is not in anyone's interest. In fact, taking them out of circulation would be extremely bad. Hard to communicate how bad this would be. Pretty much a crossing the streams/total protonic reversal outcome.

Could bad outcomes be prevented? Stunts like what was done with Indian currency, or a move to all-digital currency? I don't see it.

Since hoarding of the polymer bills seems like a likely outcome of negative rates hitting consumers, and this would be bad, and in the absence of other preventative measures, I highly doubt we'll see negative rates at the consumer level.

When the economy was roaring a couple years ago the Fed was starting to bump rates up it shook the markets bad. Started ratcheting down since.

If they can somehow get inflation higher then I could see rates moving up a bit. But it just hasn’t happened. So much of the rest of the world has lower rates (much lower) as well.

Also, Trump or even his successor might juice the economy quantitative easing, meaning that cash you are saving in the bank becomes worth less anyways. This isn’t an easy decision to make.