True, and it's the most likely option.
Nonetheless, all options on the table are bad. Any kind of war between India and China will be catastrophic, even if it was a proxy war involving separatist groups.
It'll affect both countries in addition to other countries in the region. All countries in that area, including Pakistan, Iran, Afghanistan, China, Kazakhstan, Russia and India, have separatist groups.
If it all goes down the shitter, that whole region will look like a bigger and uglier version of Syria and Iraq.
Honestly, it's easy to talk about wars without consequences on internet forums. In real life, it's going to be very ugly, and everyone will lose. Well, everyone except America. The US would absolutely love it if all these emerging Asian powers fight one another to the point of destruction and fragmentation.
Are you? You're the one who thinks a nuclear war between India and China is a laughing matter and that it'll only affect India. Hello, it'll destroy both countries. You will suffer as much as your Indian counterparts.
Good grief! Thank god you're not in charge of the nuke button.