How to handle C++ versions?

[CreRecombinase]

I took a look at cxx11.json and noticed that it doesn't do anything. I was wondering what a cxx14.json, or cxx17.json (and coming in May cxx20.json) might look like. In theory it should be possible to to use a different C/C++ compiler for one package, in which case this would look more or less like any other dependency, right?