'tis why I said "linguistically."
Study of Sanskrit truly and academically began in the 15-16th century, if I'm not mistaken, and didn't really take off until the 17th. It is not necessarily akin to tradtional European study, as Latin and Greek are.
I like your supplemental requirement--should a language be studied by others after the native speakers are no more, then yes, it would fall under our "classical language" category in the academic world.
Now, as an admin, where do you stand on adding other "classical" languages to Textkit