>1,2,3

IMO American hubris to assume PRC would leave US basing alone, especially in region. In event of PRC blockade (war), it's all fair game and JP/SKR much more vunerable to external dependencies and in terms of industrial base and resources, PRC sheer size can survive attrition better vs SKR and JP. Attacking these forces result in US entering first island chain, which is better than the alternative of trying to break blockade where US is strongest. Ultimate PRC stretch goal goal is to eradicate US east asian security architecture, so there's more reason to hit these bases than not. Either US comes to rescue of allies in region where they are weakest or they lose credibility.

>Which they won't do

More likely they will, it's spelled out in doctrine in latest PRC Science of Military Strategy. Again it's US hubris to assume only US can strike PRC mainland targets with impunity. Keep in mind US short/medium range strike platforms are all nuclear capable, but no one thinks PRC will retaliate with nukes to US tomahawks. Assured second strike exists because no one will trigger hairstring immedidate retaliation if they know adversary capable of conventional strikes. Hence PRC work on hypersonics, because realistically it's the only conventional platform that can hit CONUS, while simultaneous building up nuclear forces and maintaining No First Use to setup posture for conventional CONUS strikes. I think we're in for serious shits if US planners assume only they can strike PRC mainland and expect no retaliation.

>US intelligence will see movement of Chinese forces

Hypothetical PRC PGS can preempt strike with ICBMs (again doctrine for long time, though less likely) without any pre-position or visible signalling. Roll out TEL from tunnel and any target around globe can be hit within an hour. Even if discovered immediately it would take longer for ships pull out of port. Also most of US ships especially support aren't nuclear, which means they need continuous replenishment tail which are extremely vunerable. Hence point about taking out fast combat support ships (which exist in single digits) basically cripples all of USN. Escorts of CSG underway can't sail for long and become stationary single use VLS platforms assuming they can make it in theatre at all.

>This doesn't make sense for a few reasons
...
> attack on the continental United States

It makes perfect sense for PGS use case, that's the entire rational behind PGS for US as well. There's no survivable shelter (except maybe bombers / SSNs) for strategic assets because every platform needs to stay still at some point for maintanence. Again the goal is to establish mutual conventional vunerability to deter US by making attacking mainland PRC as risky as attacking CONUS. It only doesn't make sense from US exceptionalism lens that no country in the world would dare to hit CONUS. That's historically true due to technologic limitations that prevented accurate (non nuclear) fires against Fortress America that's geographically isolated. But assumption will not hold when PRC (and eventually others) acquires accurate PGS capabilities.

> don't dock at the same time

No but they all dock eventually and will be therefore subject to attrition and become single use assets that can't sustain power projection. It's logical extension of PLA systems destruction warfare that targets AWACs and other critical subelements that would cripple US warfighting capability. The caveate being that PRC can bunker away enough survivable ICBMs for the weeks/months US ships can stay out at sea, and that's assuming kill chain for hitting moving ships at sea is dud.

> cyber

PRC will anticpate US retaliation, but functionally it enables PRC to dish proportional damage. Again, it's about mutual vunerability. The broader point being that we are in era of conventional MAD in other domains. Having a massive blue water navy isn't going to save US society from existential damage unlike in analogue era. US always had conventional capablities to hurt PRC and others with CONUS impunity, but they maybe deterred if PRC can hit US conventionally or via cyber as well.

> US has shored up allies

US tried/trying to, but so far there hasn't been any meaningful movement in region except words. Certainly nothing substantial like IRBMs or AGILE basing that makes US assets survivable and that's among US allies. Surprisingly no one wants to be PRC missile sinks for US. Everyone else is neutral / hedging. The crowning achievement is AUKUS that establishes new US capabilities all the way out in west AU which is farcry from initial US blob hopes of having IRBMs in every ASEAN country. Alas no taker because PRC aggressive diplomacy works. Regardless, doesn't change the fundemental changing force balance - trend is PRC will simply have more forces in theatre than US + co can hope to aggregate over time.

> no chance of reunifying now

Not peaceful no, but that's inevitable nature of demographic/cultural shift between different political systems. Status quo preferrable but TW/US stirring up status quo or at least reverting it to less stable arrangement (PRC is one content with 92 consensus charade). As for taking TW, if US deterred, PRC can simply turn the island into Yemen/Palestine and drag out capitulation without single boots on ground. No amount of porcupining can prevent that. I think UKR/RU and past US excursions has shown massive loss of life quickly tolerable. At end of day, it's an ongoing civil war with US playing offshore spoiler for last 70 years with no simple ending except force. It's not preferrable, but it's what's left if TW/US doesn't play ball.