OK, I'll try to wind this down and not speculate further, I did not intend to derail this forum thread. I wanted to raise questions to this forum because I really do think it is more likely than not that this scenario occurs in the next ten years. Unfortunately I have not seen any definitive answers from the forum members here like I was hoping for, or any creative strategies China could pursue to mitigate potential risks or deal with them as they arise. Everyone seems to jump to first strikes or MAD scenarios as a response, which is unsettling in my opinion. The inability of forum members here to propose solutions to this potential threat validates my fear that the scenario I described in my posts (US proliferating to allies) is indeed a no-win scenario for both China and the world as a whole, which is why it is frightening and offensive to talk about.
It's quite frankly strange that you thought someone would have a better strategy than MAD or to snuff out nuclear sites in a pre-emptive strike or to further improve Chinese military technology. It's fairly obvious that there exists no better answer than these 3 in the world to a nuclear adversary and all 3 work quite well.
Rather it sounds like you came here with a question you know was unanswerable by nature (at least to a degree of bloodless checkmate perfection), and when given the best answers in the world, you tried to make it sound like because they aren't ideal, therefore it validates your argument, which is totally farfetched and not worth entertaining because there are no signs of things going in that direction.
This only works if the nukes are on Taiwan or any of the territories under control by Taiwan. If Taiwan had SSBNs in the deep pacific, or even fast attack subs with nuclear tomahawks or equivalent, it would mean that China has no reliable way to prevent a retaliatory strike (except air defense, which is risky when nukes are involved).
First of all, with China's current rise and trajectory of its power, it may be able to strike (with confidence that the US dares not fight or cannot win) when the ROC announces its nuclear submarine program before they are fielded, if they dare to embark on such a provocative program in the first place, which is a fantasy now. Secondly, with the ROC's budget, even if they make these subs, they can't afford many, and the PLAN can specifically track these 2 or so subs and kill them when the opportunity presents as the opening move to a conflict. Finally, that some casualties may be suffered in a war to retake Taiwan was never something that the PLA ad shied away from saying that it will trade every city with the US in a nuclear war over the ROC. When the CCP issues the ultimatum, the calculus for the ROC remains the same: reunite or be destroyed. Whether it can get a few shots off and cause some casualties in the process is a detail.
Being a small nuclear power can deter bullying from countries like the US always looking for soft easy targets but it does not change the balance of power against a large nuclear country that is determined against this specific target and that is precisely the situation in the case of the ROC.
This concept has been the basis of deterrence for both the US and USSR/Russia for half a century. Unless China can manage a synchronized, simultaneous strike to eliminate all nuclear threats in the region, those threats act as a strong deterrent to China using force to reunify Taiwan. It may very well be the preferred strategy by the US to engage in nuclear brinkmanship when the US and its allies realize their conventional forces cannot defeat the PLA, especially as the PLA continues to grow more powerful in both conventional and nuclear forces. Such a strategy by the US would mirror exactly what the US did to the USSR half a century ago; they realized they could never defeat the red army in conventional warfare, so they went all in on nuclear deterrence in Europe. Being the fossilized remains of cold war ideology, Biden may set the US and its allies on this same course in Asia.
The Soviets were never defeated by nuclear deterrence; they never wanted to go to nuclear war. The Soviets were defeated by economic failure.
The DF-15 and similar ballistic missiles that the PLARF currently has would take about 5 minutes from Fujian to Taiwan. I believe that PLAN sub launched cruise missiles off the coast of Taiwan could hit any part of Taiwan in less than 3 minutes. This is too fast to be reliably countered by a launch on warning posture in Taiwan, unless the button pushers are free to fire without obtaining explicit permission by the chain of command. As such, Taiwan can never have a survivable land based deterrent.
Being a small island a (military) stone's throw away from China, facing a determined China, there is no real effective deterrent once it becomes obvious that the US cannot win the war for it.