I have no doubt that the PLARF land-based ICBMs will continue to be an integral part of China's nuclear deterrence, but one cannot deny that sea-based deterrence is, pound-for-pound, the most sought-after and capable arm of the nuclear triad, especially when US satellites are almost certainly keeping close watch on all suspected Chinese missile sites.
The 300 silos may signal an increase to their land-based platforms but that in an of itself isn't any indication that China has shifted its priority from SSBNs to land-based ICBMs. The shell game theory is interesting, because if it turns out to be true, this could actually signal a reduction in their land-based ICBM arsenal.
Sea based deterrence has its role, and is most ideal if you have:
- A competitive and capable SSBN and SLBM capability
- A comprehensive degree of peacetime sea control and naval dominance in your regional periphery to allow your SSBNs to operate and deploy relatively safely without threat of consistent close in monitoring and detection
For the PLA, the first one is a matter of time, money and industry.
But the second is much more difficult and a longer term process dependent on geopolitcking, and is not guaranteed.
So yes, I absolutely agree that SSBN+SLBMs will play a major role in China's nuclear deterrence going forwards once they have a competitive and capable SSBN and SLBM, but the "pound for pound value" may actually be significantly less for China than it is for the US due to the second factor of regional presence of adversary forces.
As for the silos -- my point is that with the existence of those 300 silos, we can no longer speak of "China's hesitance to expand its nuclear arsenal"
as if it is definitively confirmed that China is not currently expanding its nuclear arsenal.
Right now, the question we should be asking is what the status of those 300 silos will be, if/when they will be fitted with ICBMs, how extensively they will be equipped, and what sort of missiles and MiRV status they may have.
In short -- existence of those 300 silos means we are obliged to ask "
is China expanding its nuclear arsenal" rather than "why is China not expanding its nuclear arsenal".