That is your subjective opinion. Hindi has shown the most growth than any other language. It has also made inroads in Kerala and TN but people are not ready to see it. Hindi becoming Lingua Franka is never the effort but growth in Hindi speaking region itself is the biggest assimilator. A cocky South Indian living in his own cocoon may be happy harping on Tamil superiority but as the markets are expanding and becoming interdependent each language is getting its own share of value with only Hindi expending.