Seconding this. I'm now unable to use CAPS LOCK on my Mac as ESC, which makes using vim slightly more of a pain.
Why? The real thing has been out since September 20.
Hence why Seil/KarabinerElements is the first thing I install on a new Mac.
https://github.com/tekezo/Seil/issues/68#issuecomment-250195...
I really did not expect Apple to finally fill this gap that has been around for so many years.
I was using Karabiner to set caps lock to control AND escape when pressed independently, something extremely useful to use Vim and command line. This doesn't appear to be supported, unfortunately.