Well put.
I think that the Chinese army is far larger than that of India, despite the populations being about even. The Chinese would probably find a ready ally in Pakistan, but then again, China has a growing problem with restive populations in its western and northwestern reaches, and can’t afford a war with India. India’s armed forces are probably better than those of China, but China has a numerical advantage. That served them well in the early months of the “volunteer” Chinese invasion during the Korean War, but ultimately their losses were massive and defeat was near-total.
Also take into account the fighting spirit and capability of India’s Sikhs, who are a minority in India’s armed services (army, navy, air force).