With the exception of India, all countries (including Vietnam) with land borders with China have agreed upon the demarcation of their land borders.
The tense era was from 1950s to 1980s, since then the only area of possible war is between North and South Korea. China now is more friendly with South Korea than the North. I am not even sure if China wants to involve. They may even wish the North gone.
And I do not foresee any war between China and India, but if an unlikely war erupts in Himalaya range, heavy tanks are not of much use in rugged mountains unless India send troops across into Tibetan Plateau.
Agreed. Although not about China not getting involved in a war in the Korean Peninsula. Whose side China will fight on, now that would be a very interesting question.
Personally, I think one of the main contingency plans, and the one the Chinese leadership is likely to lean in favour of, is a grand bargain with South Korea.
If NK does something so monumentally stupid as to make war inevitable, I think there is a strong chance China will secretly make SK an one-in-a-lifetime grand bargain:
The PLA is going into NK. The question is which side they will fight for. Agree to ditch America in favour of China as its diplomatic and military backer, and the PLA will enter NK as allies of SK to end the war once and for all, with minimal deaths and destruction, and China will even help with post war reconstruction and modernisation of the North.
Between them, China and SK could probably neutralise NK's nuclear Arsenal before it could be used, which both would be supremely keen to see happen.
Refuse and it will just be a re-run of the first Korean War.
The PLA will go in mainly to end the war as quickly as possible, and minimise the flood of refugees into China, but also to help SK keep its part of the Gand Bargain after.
But that is just speculation on my part.
Bringing things back on topic, unless you have been living under a rock for the last 30 years, you must know that the key to victory on land in the modern era is control of the skies, or st minimum, the ability to deny your opponent control of the skies.
The biggest and best equipped land forces are still going to get reduced to so much scrap and dead bodies if you allow the enemy to control the skies, and so can bomb your ground forces to ruin at their leisure.
Conversely, so long as your ground forces are not neglected to the point of uselessness, any half decent ground force can easily win the day with friendly air power secures the skies.
Even the humble venerable Type 59 is enough and wins by default when the enemy's fancy M1s or Leo IIs have been slagged by your Air Force and attack helicopters.