Biggest military challenge for India is a two-front war against China and Pakistan, we know it and they know it. If a war is to break out between China and India over "southern Tibet"/"Arunachal Pradesh" it could very well entice Pakistan to join depending who is the COAS and Government party in power, not to mention Chinese government may very well encourage and message Pakistani Government to do just that. It's neither in China's interest nor Pakistan's interest for India to hold onto the remaining part of Kashmir and southern Tibet. Nor do I think China's future plans will accommodate a regional power India which can challenge Chinese navy in the Indian Ocean. Hence, many Chinese Think Tanks repeatedly publish breaking India up, starting with the north east Indian provinces which are the easiest provinces to liberate from India. China is asserting it's economic power in India already in the forms of investments where Chinese own large shares of companies inside India and the military infrastructure China has built along their southern border with India is indicative of the importance China gives to that front and potential for a war in the future.