I'd love to see support for Conan, the C/C++ package manager.
Our company mainly works on embedded software (which is where Conan comes in to play), but we also develop some accompanying desktop apps every now and then using C# (for which we want to have a NuGet feed).

There is an open source implementation of a Conan server available and both Artifactory and Sonatype (via an open source plugin) have support for these kind of packages/feeds.