Breaking the blockade would be extremely difficult to do for a variety of reasons. Primarily, unless the US was willing to attack mainland China, there's no way they could overcome the PLA/PLAN. And if the US attacks mainland China, the risk of the conflict going nuclear rises exponentially.
If I were the PLAN, I would focus on three areas; MRBMs to keep the CVNs far far away, airpower over the region to keep Japan out, and submarines to enforce the blockade.
They currently have enough DF-21 to make the USN very skittish about approaching within range of current carrier aircraft. There are countermeasures to the DF-21, particularly the targeting chain that can be disrupted, but that's dicey.
The PLA currently has enough aircraft in the region to gain air superiority, though not air supremacy.
Submarines are the real wild card. The US Navy's SSN fleet is stretched thin, and is in declining numbers compared to the PLAN fleet. Qualitatively, the USN is far superior, but...
In terms of other ASW assets, the USN is woefully unprepared for fighting against an opponent with home turf advantage. The CVNs no longer carry organic ASW assets, and have lost a lot of the institutional knowledge learned during the Cold War. The surface fleet has also let ASW skills atrophy.
All these combine to make it very unlikely the US would attempt to overcome a blockade in the next decade. If the US were to invest a significant amount of money above the current baseline in shipbuilding, this calculus might be different.
For a country dependent on US controlled shipping lanes to obtain food and oil, as well as dependent on the rest of the world's financial system to keep their population employed, it's a bit ludicrous to think of them blockading anyone. China is the one who is vulnerable to a blockade - it's not even food independent.
I'm sorry, but this statement doesn't compute. The Belt and Road initiative is an attempt at exporting infrastructure services as they are already exporting all the tradeables they can, so to keep employment going they are trying to export, say, bridge building by sending Chinese workers overseas to build bridges, ports, roads, etc. in other countries.
The terms of the deal is to always be paid in USD -- USD which is held in custodial accounts in the US. Thus it is a roundabout way of exporting to acquire more foreign currency reserves. But the moment there is any kind of conflict, all of China's foreign reserve holdings are likely to be seized in the worst case and frozen in the best case, so the fact that there are bridges and ports all over Africa and Southeast Asia built by Chinese workers isn't going to help China import food or get past US control of shipping lanes.
China is not principally buying money, its buying geopolitical influence; nations that see their interest aligned with China succeeding in competition with rival powers.
It is not principally buying money, as such a thing is impossible in a nation with its own fiat currency. Rather, it is creating jobs for their domestic population. The foreign currency reserves are not the objective, employment is the objective. This is true of all export-led-growth strategies. China already has more than enough foreign reserves by any possible measure, and it can't really do much with the reserves it has - it has to sterilize those which creates inflation and forces China to go into massive RMB debt when they sell domestic bonds to sterilize the foreign inflows.
But neither is it buying influence overseas, as these projects are wildly unpopular and result in unsustainable debt burdens and massive amounts of ill-will. If you look at a map, you see most of these projects happening in authoritarian nations or nations where there is a lot of corruption, and what happens is that leaders force their country into unsustainable debt burdens while they themselves get bribed. Then when they leave office, the nation will default and now it will be an enemy of China. It's like China's project to extract resources from Africa -- lots of ill will and anti-Chinese feelings are created from these projects. It certainly does not cause their foreign influence to increase, but it does create jobs for Chinese workers, which is the point. The fact of the matter is that the Chinese construction industry has already built far too many airports and ports that China can use domestically, so as with the manufacturing excess capacity, the excess capacity of the construction sector is being offloaded onto the rest of the world, primarily to third world nations that can't afford these ports, and it is happening at the expense of lots of ill-will.
What would be in China's interest would be shrink its construction industry and try to re-allocate to providing healthcare, senior services, and other services that China's own population needs. The sooner they stop exporting excess capacity in all these industries the better. That would also do much to at least stem the tide of anti-Chinese resentment that is created by these projects in which excess capacity is dumped onto the rest of the world. Don't underestimate the long term damage that these projects are creating all over the world to China's image.
If you project out USN shipbuilding plans to the end of this decade, and then do the same to for the PLAN, the numbers get concerning. Ships take a long long time to get built, and the PLAN has a very high construction tempo.
If I were the PLAN, I would focus on three areas; MRBMs to keep the CVNs far far away, airpower over the region to keep Japan out, and submarines to enforce the blockade.
They currently have enough DF-21 to make the USN very skittish about approaching within range of current carrier aircraft. There are countermeasures to the DF-21, particularly the targeting chain that can be disrupted, but that's dicey.
The PLA currently has enough aircraft in the region to gain air superiority, though not air supremacy.
Submarines are the real wild card. The US Navy's SSN fleet is stretched thin, and is in declining numbers compared to the PLAN fleet. Qualitatively, the USN is far superior, but...
In terms of other ASW assets, the USN is woefully unprepared for fighting against an opponent with home turf advantage. The CVNs no longer carry organic ASW assets, and have lost a lot of the institutional knowledge learned during the Cold War. The surface fleet has also let ASW skills atrophy.
All these combine to make it very unlikely the US would attempt to overcome a blockade in the next decade. If the US were to invest a significant amount of money above the current baseline in shipbuilding, this calculus might be different.