Not really my opinion, per se, but rather a point of fact:
The very first thing that would take place is the movement of personnel, and assets to coastal staging areas. I see no way that this can be carried out in total secrecy, given the level of surveillance that China is constantly under.
So, we then have to assume that Taiwan and her allies are aware of the PRC's preparations and general dispostion, and are making moves to counter.
We have to assume that the American, Austrailian, and Japanese response would be to defend Taiwan, because they stand to lose more if the PRC manages to capture or destroy the ROC. They have the intelligence, strike assets, and the ability to project power. A Coalition to defend Taiwan can be quickly assembled, with little reason for international backlash or interference- defending Taiwan from unwaranted, overt PRC aggression is an easily defendible position at the UN.
We have to assume that the American carrier task force in Japan is placed on alert, and/or preparing to deploy in force. Any other available groups and units in the region are also being tasked, and Taiwan's defense forces are digging in.
Without maintaining total OPSEC, the PRC is already fighting an uphill battle- even if they have the initiative, and overwhelming numbers.
One variable is unknown: The PRC's vast number of conventional, and nuclear-tipped ballistic missiles that are already targeted at Taiwan.
If the Chinese are truely commited to retaking the island by force, then we should probably assume that they would prepare the battle space by missile bombardment. They have to soften Taiwan's defenses, maintain their offensive momentum, and attempt to crush morale.
So, it's likely that a number of missiles will be launched in the opening hours of an invasion. The success of these strikes, or the effect they have on Taiwan's defenses is a real question at this point.
But these missiles are a major issue, and if they are used- they could make all the difference towards determining the outcome. Suffice to say, bombarding Taiwan with ballistic missiles would be viewed as a very serious escalation, and the international backlash could be far worse than China is prepared to withstand. Collateral damage and casulties are a certainty, and that won't help China's position at all.
If China is so motivated to reclaim the province by force, they will have to pay for it in blood, and face the consequences in the arena of international politics.
Of course, if the PRC are so brazen to use nuclear warheads at any point- their ultimate destruction becomes a foregone conclusion. There can be no reconciliation or justification for attacking Taiwan with nuclear weapons, and the hammer will fall swiftly and hard in retribution for such a criminal act.
Now, I see no reason for Coalition forces to attempt to dominate and secure the staights- to do so places men and equipment at unnecessary risk. Carrier, and surface action groups should remain a safe distance away to the south and east of the island. SSN's, and FFG's/LCS(?) could possibly operate closer to the island, interdicting PLAN subs and other targets of opportunity.
Taiwan's military should be expected to defend their territory only, and to hold the line on the beaches.
The Coalition forces merely have to deny the PRC access to the straights by designating the waters and airspace between the mainland and Taiwan as a free fire zone. Any air/sea/sub-surface contact in the exclusion zone that is not immediately identifiable as a friendly, becomes a target of opportunity.
Long-range AAM's and SAM's from Coalition air and sea assets should be instrumental in destroying PLAF fighters and bombers, allowing ROC air defences to target whatever else the Chinese have pressed into service as a troop transport. It goes without saying that airliners, cropdusters, and fishing trawlers aren't going to last long once they come within range of the ROC's long range missiles- and their artillery, ATGM's, and MANPADS should be able to finish off any survivors with relative ease. ( As long as they can continue to supply their systems with ammo. )
By attriting whatever Chinese forces that attempts to cross, China would be forced to attack the supporting Coalition task forces in blue water. Naturally, this places China at a further disadvantge- These navies dominate in blue water enviroments. Additionally, the further away that the PRC forces must extend from the mainland, the greater the strain to their offensive operation.
It's likely that massed fighter and bomber raids against carrier groups would be one-way trips for the PLAF, and those are assets they cannot afford to lose.
In addition, the Coalition ( US forces in particular ) can further destabilize the PRC's invasion plans and operations by attacking her garrisons with force enablers/multipliers, and strike assets. They can initiate these strikes from stand-off range, without warning, at any time, with a very high PK per sortie- perhaps before the main elements of the invasion force are even underway.
If the PRC's airfields and port facilites in the theater are affectively put out of commision by Coalition strikes- their ability to project power, recoup losses, and launch further offensive operations is greatly diminished.
Meanwhile, the ROC forces are at their highest level of readiness, and can focus their attention on maintaining the strength of their ORBAT, defending beachheads and landing zones, and using their longer-ranged defenses and weapons to attrite the PRC's units as far from the island as possible.
By holding the majority of their hardware in reserve, and under shelter from PRC air, and missile strikes- the ROC should have sufficient forces availaible to smash anything that manages to survive the crossing.
I'd surmise that it is possible for the PRC to retake Taiwan- but only if they are willing to pay a very great price, and prehaps even risk their own destruction in the pursuit.
One thing is certain- In the end there is likely to be at least one less country when the smoke finally clears.