I liked the Reference Assistant extension very much, but unfortunately it only works for Visual Studio versions 2010 through 2013, and I always wanted to adapt the extension to later versions of Visual Studio.
Now I did.
So I forked the original code from the repository on GitHub (really originally hosted on CodePlex).
Since I had no experience in working with the VSSDK, I created a dummy project and clicked my way through it, and tried to figure out, where the original code hooked into VS, and how to migrate that code from 2010 to 2017.
One of the main obstacles was the setup of the Options page, which seems to have changed fundamentally. Fortunately, the Extensibility Samples also contain a project named Options covering the Tools->Options dialog.
Of course, migration also means upgrading .Net versions (implied by creating a VS2017 extension project), replacing assembly references with NuGet packages, and a little bit of tuning and tweaking.
You can find the upgraded Reference Assistant on GitHub, the first release version is here.
What I like about this tool is that is lets you preview the changes it is going to make, and exclude references from removal you know are required, as the tool does not consider occasional implied references and assemblies referenced in .config files.