The world will not unite against China in the delusional understanding that the US is good and China is bad. China will not roll over and get flattened like an Afghanistan or an Iraq. Nobody knows what will happen, but it will probably be horrific.
[0] https://www.uniassignment.com/essay-samples/history/attitude...
I think the more interesting scenario is tech embargoes taking away the "building blocks" (e.g. chips) and stalling their tech production. But China is well aware of their deficiency in this area and they've been pushing hard towards what they call "self-reliance" [1].
As for food, I can't imagine the conflict escalating to such a level of hostility and disregard for human life that the world allows the US to blockade China into starvation.
[1] https://www.bloomberg.com/news/newsletters/2020-10-31/bloomb...
https://www.scmp.com/news/china/diplomacy/article/3012888/ch...
Also, China is in bad terms with almost every other neighbor it has (territory disputes with almost every one).. and they will be glad to see it humbled a notch or two and will not help.
China would be more than happy to help those countries with better "air defence".
Joke aside, the real question is: will US wage war on China for Taiwan.
I think it's highly unlikely.
US and Europe align within a few % when it comes to anti-China sentiments. US is 7th after Japan, Australia, Sweden, Denmark, UK and South Korea.
On the other hand, given current US political status, they might actually want a war despite the risk.
"Negative sentiment" is not cause, it's propaganda for the possible declaration of war.
If China invades Taiwan, US will defend it*
You would need to ask China if it's worth the trouble.
* that is if China doesn't fail as miserably as it did with Vietnam where it declared victory after retreating
https://www.google.com/amp/s/www.forbes.com/sites/kenroberts...
The us also is generally less dependent on foreign trade than most other countries. Huge domestic market.
It will be blockaded itself, as the US can within 48hrs blockade all commercial traffic in and out of china. China doesn't have much oil by itself, and it needs imports to properly feed its population.
It will end up like those scenarios, where the sieging forces, get sieged and cut off itself. Its navy is a near-shore force, and just can't project force outside the China sea. They can completely control the part of China sea near about 200-400km near its shore, but it will be unable to go any further than that.
It might end up like a Japan, 1941 scenario. They might be able to score some early surprise wins, but on the long term they are doomed to lose the war.
Ps. While china is experiencing a boom like the 50s and 60s in the USA (lots of infrastructure being built), China's demographic is aging, and we might see a scenario that the current boom will just slow down, and itself end up in a situation like Japan in the 90s, or USA itself in the 70s. It will reach a peak in the next 10 years (economically) and start leveling off to more normal rates of growth.