The US economy will be in ruins, and nothing can stop a large scale military conflict.
Right. Fab tools require constant maintenance. I'm sure they keep a stock of repair kits and spare parts, but probably no more than a few months supply. Their supply chain ops (procurement and engineering) sets min/max stock levels of these parts, but I'm willing to bet that there's no more than a few months supply on hand. And then equipment gets dirty, wafers get scrapped, yield plummets, etc.
Signiciantly more will be suffered by US/west whose advanced industries extracts disproportionate patent fees and have extreme reliance on TW semi for short to medium term. We're talking trillions in knock on effects. Proximity of semi production / supply chain concentration in TW and broader east Asia is PRC's trump card in war. During peace US has trump card in sanctions / tech control, but during war PRC has leverage of simply setting the advanced economies back 30 years which will actually close relative gap. PRC might even pull ahead if they manage to mass rollout of 28nm indigenous fabs and complete indigenous semi supply chain before anyone else. That's without mentioning during war, PRC has incentive to attack SKR/JP fabs to draw US into first island chain where they're weakest to honor security commitments. If things ever get heated with US, it would be insanely smart for China to threaten TW/JP/SKR as well. And if PRC attacks TW, I surmise there's going to be three way side deal between PRC, US and TW leadership to maintain TSMC production continuity in exchange for evacuations for TW leadership to US who would otherwise get the noose for treason. Which itself makes the notion that TSMC is rigged to blow counterproductive - surival of TSMC is TW elites golden ticket off the island - US isn't going to look kindly to a TW admin that explodes US economy and tech lead.
People can live without smartphones, but can't live without food. In case of war, westerners will need to postpone buying some electronics or clothes, but the Chinese will resort to severe food rationing.
Another Q one should ask is how vunerable US is to comparable counter action. Because US agriculture is highly industrialized and automated whereas PRC ag is in the process of automation and still reliant on labour. Sufficient cyber attack on US ag infra during harvest season and US is forced to ration. What happens to automated John Deere tractors when they have no GPS to harvest. Same with familiar threats of embargoing PRC oil because US is self sufficient on the metric that there's enough fossil fuel resources in the ground. US is only as self sufficient as how much it's 130 refineries can produce. If US interdicts PRC energy, don't be surprised if PRC takes down comparable levels of production state side.
As for cyberattacks from China, those can only do so much, and in any case they can be mitigated by cutting the fiber. OTOH, shooting down GPS sats will lead to war. They know better than that. I hope.
It's unlikely China or Russia, or anyone, has the capability to shoot down GPS sats. A number of countries, the US included, have demonstrated capability to shoot down satellites, low orbit satellites. GPS satellites are in geosynchronous orbit, which is a whole different species of animal. Shooting down an LEO satellite can be done with an SM-3 missile which has a mass of 1.5 tons. That's significantly lower than the mass of a rocket needed to put the satellite in orbit, and that's possible because SM-3 is not designed to reach orbital speeds, only orbital heights. Its primary mission is anti-ballistic missile defense and ballistic missiles can reach thousands of kilometers altitude, but not tens of thousands.
In theory one can design a missile that can reach GSO heights without reaching GSO speeds, but that requires a dedicated project, which would be extremely expensive, and very difficult to keep under wraps. All missile launches are pre-declared to minimize the risk of a nuclear war. You can find a list of all orbital and suborbital launches on wikipedia (e.g. [1]). If anyone tried to test a missile that can reach GSO heights, they couldn't keep it a secret.
One can then try to shoot down GSO satellites with full size rockets, like Falcon Heavy. But there are 31 GPS satellites out there, and 30 Galileo. I doubt either Russia or China (or even America) have 60 full size rockets available to do a blitzkrieg strike against the GPS satellites.
[1] https://en.wikipedia.org/wiki/List_of_spaceflight_launches_i...
This is in event of an war.
Legally, so is blockading PRC, including food and energy imports which is not an unfamiliar discussion in US policy circles. As for cyber, US DoD / Biden also explicitly communicated to both PRC and RU that cyberwarfare on critical infra = actions comparable to war. I don't know if cutting fibre is a joke, there's millions of PRC diasphora, unless US disconnects from internet globally, that's assuming PRC agents aren't state side already. So the real question is, does the US know better than to intervene when PRC attempts armed reunification with TW, which seems increasingly likely while bills are being drawn in congress to boost TW into major non-Nato ally? Because if US does, there's no telling how things will escalate, especially when modern connectivity and increasing PRC missile capabilities means CONUS is no longer safe. Incidentally, I think both sides knows this, on paper but frequently, better judgement gets overriden by domestic politics.
To make it easier to understand, total world grain production is about 2250 million tons for a population of 7.8 billion. At worst China would need to ration more expensive meals, but people wouldn't starve.
Furthermore, it probably also means the disintegration of US global sanctioning power. Europe would rather trade with China than the USA, assuming it's mutually exclusive.
https://www.usnews.com/news/world/articles/2022-07-30/swiss-...
They might get six or twelve months of production out of TSMC's facility, and then things will start to break that they will not be able to fix easily. Invading Taiwan will cause economic damage measured in hundreds of billions of dollars at a bare minimum, and much of that damage will be suffered by China.
Bottom line, it would be insanely stupid of China to attack Taiwan. Of course, many people (including myself) said the same thing about Putin and Ukraine, so...