[jcranmer]

I predict IPv4 will be widely considered legacy before decimal floating point numbers are common place, let alone binary floats being considered legacy.

From what I've seen, there's just simply no demand for decimal floating point; there's basically one or two people who ask for it, and this carries up all the way through to C committee standardization. Far more people care about things like non-default rounding mode or exception support than care about decimal floating point, and that's an area of floating point that itself is pretty damn low on people's priority lists.

The advantage of decimal floating points is that it fixes the rounding error when converting to/from decimal strings... and that's it. It doesn't fix non-associativity, it doesn't fix gradual precision loss, it doesn't fix portability issues because different libraries have different precision targets. And you get this for the slight cost of making every single floating point operation slower.

And here's the other truism about floating-point: most people who care about it value speed over correctness. There's strong demand for operations like approximate division that don't do the refinement steps, and consequently throw away half the bits. Fast-math flags are similarly pretty common, because users already aren't expecting bit-precise results, so the resulting changes in precision are quite often acceptable for them.