When USA declared West Philippines Sea. China spanked Philippines and grabbed Scarborough Shoal. When USA declared Senkaku Islands, China spanked Japan and shattered their de facto control with airspace and territorial water intrusions. Now USA declares Arunachal Pradesh....... 
Chinese leaders know it very well that Arunachal Pradesh was long gone. They are now doing everything not to lose Tibet. Just for face saving purpose, Chinese leaders are not declaring Arunachal Pradesh as part of India because, they fear, it might cause domestic uprising against their decision and also put them in a place where they will be looked down upon by all other small neighbors of China. So the question is whether Tibet will with China or India and if USA will help India annex Tibet.
Well, USA has been supportive of the view that Tibet should be with India since the years preceding 1959. Why USA wants Tibet to be with India is a different question but India would annex Tibet with or without help from USA. The effective weapon that India uses against China in this case is the Tibetans. China missed the chance of using Tibetans against China's enemies because China could not tame the Tibetans and integrate them with the Chinese national philosophy. China does not believe in a single nation which includes different minorities. PRC is a conglomeration of different nations and this is why China still officially recognizes Tibetans as another nation living within the Chinese geographical boundary. So officially Tibetans are still called Tibetans in China, not Chinese. In India the case is totally opposite, after the annexation of Sikkim, Sikkimese were called Indians, same way, all other NE peoples are called Indians and it is considered as an act of treason if someone identifies himself non Indian while having Indian Voters identity card, ration card, passport, pan card or other similar identity cards. Such persons will be considered terrorists and will be punished severely.
Its China's fault that Chinese leaders could not play cunning moves to integrate the Tibetans within the Chinese nation making process. If I were the supreme Chinese leader, I would have used the Tibetans against China's enemies and for that I would have played various cards be it race, religion, political ideology etc. This is how you make a nation and protect it from outside forces. Constant fighting against enemies is an ingredient in the process of nation making. People should always be engaged with serious tasks and if they are not, they will give you trouble. Wars are the most effective way of engaging people of the peripheries because as long as your peripheries are fighting against your enemies located at your border, you know your nation state is intact.
that is what you could do ? 
