Update -12/21/2018 by anangaur: Spec

Original comment by @daveaglick:

As NuGet gets older, I've noticed a pattern where some packages have a description along the lines of "This package is old and shouldn't be used, use XYZ instead". It seems reasonable that as projects age, their packages may change names, split, combine, etc. over time. In fact, I'm faced with doing this for a number of packages myself soon.

I propose a feature where we can mark packages as deprecated or obsolete. This would be different from marking them as unlisted in that they would still be available on the gallery and would still show up in search results (perhaps with an additional GUI element to indicate the deprecated state). It would also be nice to specify which package(s) replace them and show that in the gallery and also when installing a deprecated package.