They want 8, that's a pretty sizeable fleet.
It's not "small" but compared to the amount of ASW assets the PLAN will have stacked in the theater circa 2025 onwards, it's not exactly large either.
Well-fortified Island with very defensible terrain, located beyond the range of most cross-straight fires, with ~160k active personnel and 10 times that in reserve.
Until and unless some disastrous moral collapse is going to happen, that's one hell of a task, even for a superpower.
Leaving aside the matter of personnel, the sheer variety of SRBMs, long range MLRS, air launched SOMs, and ALCMs and even conventionally tipped IRBMs if they're feeling very zesty, is... quite a large number of cross strait fires.
Of course, the PLA's massive array of airborne manned AEW&C/ISR/ELINT/SIGINT platforms, and UAVs, and space based ISR, means there's going to be quite significant difficulty of moving large mechanized formations around the island given the road networks (specifically the western side) without exposure. So unless the personnel are willing to operate in much smaller, dispersed units lacking substantial heavy support (and thus itself being susceptible to combined arms battalions and brigades that land with support from the aforementioned long range cross strait fires), the number of personnel itself are not indicative of capability one would think it is on paper.
The ability to adequately coordinate, move, support/supply those personnel is as important as their number, and ROC C2 nodes, logistics centers, ground formations, and sensors/recce systems will all be high priority targets alongside air bases, naval ports, and IADS radars.
Indeed, this strategy (urban/irregular warfare) is what I have been saying in different places and to Taiwanese friends in the last few years. It's the one that makes most sense from a military standpoint given the trend in the balance of power across the Taiwan Strait.
The current strategy of buying/building large and expensive weapon platforms such as F-16V and submarines is a huge waste of resources. They're more political statements and PR to show the internal and external world they're going to put up a fight. Transitioning to a urban/irregular warfare will be considered a defeatist strategy. There will also be strong resistance to such a strategy from military tradition and institutions.
Everyone's strategy is informed by politics/PR/morale considerations, so to that extent I do appreciate the situation they're in.
And submarines, even against capable foes with capable ASW have shown to be able to incur disproportionate costs or tie up resources in a conflict if the enemy happens to get unlucky.
But given the trends of PLAN modernization and given past trends of PLA modernization, one can't help but wonder if procuring these 8 SSKs will end up going the way of the ROCAF's strategy of seeking to pursue a fighter fleet that is "qualitatively superior" against the PLAAF in the 90s and early 2000s. The idea of competing for air superiority/air denial or sea control/sea denial is an attractive one, at the end of the day, because a successful strategy means your own land, cities, and civilian population and ground troops don't need to bear the burden of facing the enemy.
It's more a strategy of hope that the PLA messes up and isn't able to properly prosecute their military modernization goals, and I suppose in a "prisoner's dilemma" of choosing to forgo trying to "conventional" capabilities to compete for the air and sea, the leadership probably also believes opting to not compete at all is a higher risk than competing.
I can't see this changing for a while until the PLA's air force, navy and missile systems are so qualitatively generationally superior and quantitatively so much larger, that the cheese is smelled.
(E.g.: by the time that the PLAAF has more stealth fighters than the entire ROCAF has aircraft in general, or the PLAN having an even much bigger disparity in ASW, like 60 AIP SSKs, 60-80 MPAs, etc)
But until then, I think there is still room for avoiding the aroma, and in some halls of power it might still be seen as a viable strategy.
.... on another note, the current relative lack of emphasis PLA fixed wing CAS capability (direct attack PGMs especially), is something which the ROC military can probably try to exploit through more effective ground warfare. The PLA hasn't paid much attention to this because the PLA likely recognizes CAS/PGM interdiction requires air superiority first and the PLA is more focused on achieving air superiority against more capable foes than the ROCAF.
But I wouldn't be surprised if in coming years the PLA starts to have some money put aside to actually implement a fixed wing CAS capability... which will really begin to seal the last domains for effective asymmetric warfare that the ROC military has unless significant advances in other domains of technology emerge.
