After 60 years, India might be the number 3 biggest economy in the world, but PRC would be number 1 at that time.
The 3 land routes that they are using are tough terrains which consist of mountains of Tibet, Sands of XinJiang, and tropical forest of Mynmar, how easy will it be to attack any deeply fortified PRC military?
If PRC let Pakistan to go to war with India too, at least the Kashmir route would be disrupted. The route to Mynmar won't be easy as well. Looking at the relationship between its military and PRC, it will be very tough to get mass number of soldiers across from Mynmar into PRC. It would be disrupted just like the Kashmir route. The forests are also perfect places for gureilla warfares So the only two route that most likely won't be affected is the one through the mountainous Tibet and Sea. I not sure how well the Indian army can resupply its troops there. Now that the PRC has at least a few tough roads and one rail line currently in service, it won't be hard to the PRC to bring additional reinforcement. So the land battle in Tibet mountains would also be tough. The sea route might be easier but consider the submarine technology of PRC and India currently, the India navy might take some heavy losses before even get to 珠江口 or 海南 to confront the PRC's South Fleet (assuming PRC won't actively engage Indians ship to ship before enough submarine harassment prior).
I'm amazed to see so many people can simply say such tactics will work without any in depth analysis.