Deprecate CSSNext
Per MOox's blog about deprecating CSSNext, a switch to postcss-preset-env is in order. Given the target will be stage 0 due to the need for nesting (which I refuse to give up), the actual implementation changes are fairly light.
The only issue apparent from my experimenting thus far has been fixing some calc statements, but I'll have to refresh on everything postcss-calc was doing for me so I can revert to vanilla CSS3 calc statements here and there.
This will call for a new minor version due to the API change, but shouldn't be too daunting to complete soon.