Here's an idea for the Spartacus plugin: Does Spartacus "know" the s9y version a blog is running on? If so, we could maybe introduce deprecated plugins.
There are some plugins, whose features have been implemented in the s9y core or have become obsolete for other reasons. Likely candidates at the time of writing this would be the advanced config types Timbalu mentioned or the jQuery plugin. At the same time, there might be people still using older s9y versions which actually need those plugins. The Spartacus plugin could just skip those in newer versions.
YL