As an outside observer, it seems that combining the Tamil & Sanskrit proposals (and, perhaps, adding Hindi (and other languages of India, Nepal, Bhutan, Pakistan, and Sri Lanka)) might make for a better proposal.
I suspect that this might be a little too broad. What about keeping the two proposals, but making them into "Sanskritic Languages" and "Dravidian Languages"? Those are the two major families of languages spoken in the Subcontinent. These families are quite different - Sanskritic languages are Indo-European languages with fusional morphology, while Dravidian languages are agglutinating. The vocabulary is also quite different - Sanskrit and its ilk have many cognates with European languages such as Greek, Latin, and English, while Dravidian languages generally do not.