Why didn't india do a nuclear test, that should had detered chinkies from any misadventures.
Because that would wreck our civil nuclear cooperation negotiations. Chicoms know we have a nuclear deterrent, they don't care. They're calling our N-bluff (that we'd use them the moment they set foot on our soil), just the way we called Pakistan's N-bluff with Balakot. We didn't deny that Pakistan has nukes, we called their bluff that they'd use them against us if we hit a terror camp.
This is why I believe the so-called "nuclear peace" and MAD era is coming to an end. Limited wars will be fought between nuclear-armed nations, while the nuclear weapons will only serve as guarantee that the limited war never escalates into a total war.
We're essentially back to square one with nuclear deterrence. Let's say the unlikely and unthinkable happens, PLA overruns Arunachal, and you're the PM of India. Will you carry out a nuclear first strike (and risk a second-strike that takes out Delhi/Mumbai)? How about when PLA runs over all of North East? Will you strike then?
This is why scalable conventional warfare will be back in fashion; and India shouldn't be afraid of turning Xi's hypothesis back at him (i.e. invade Chinese territory along all points where we enjoy a tactical advantage, if they invade ours). Because then we'll be asking their question back at them, i.e. "will you nuke India and risk a second strike against Shanghai, Beijing, Guangzhou?"
Paki Op Swift DZire has a valuable lesson for us. We called their N-bluff and hit them, they took the risk of hitting back inside our territory. That is admirable. That is exactly what we must to do China.
The biggest loser with this new paradigm will be Russia, because they have many many nukes, but their conventional capabilities aren't sizable enough (to defend a country that size). 10 years from now China will start aggressive salami slicing of eastern Russia.