Ok...I'll bite.
What would be an example of a VST MIDI plug?
Uh...nevermind. I decided to answer my own question. I found some examples of free VST MIDI plugs...for instance from Tobybear. In the documentation for his MidiBag collection, he mentions that "Steinberg Cubase SX 2.0" and "Plogue Bidule", (are) two of the few VST hosts out there that actually support VST MIDI plugins.
I tried putting one of his plugs in my VST folder tree. It gets scanned and recognized...but there's no way (that I can see) to insert it in the FX bin of a MIDI track in SONAR.
(And the answer to your question is (remains)...probably No.)