Merely by the way, except under a political charade as outlined in #3, with potential opponents somehow politically and diplomatically subverted into not fighting, I personally don't think the ChiComs' have much chance of "winning", even "in the long run."
But again, that is not the question.
Another aspect of the current situation was mentioned, quite trenchantly in my opinion, by Poohbah quite some time ago—that is, from one point of view what the ChiComs may actually be doing is working on the first civil war in recorded history using nukes.
Best regards. S&W R.I.P.
And "massive nettings in isolated harbors" will not hide an invasion fleet from modern sensors--even commercial satellites will detect them. Indeed, attempting to hide a massive fleet of barges will tend to attract attention to them. Suggested reading: "The Age of Fatal Visibility," by Ralph Peters, Military Review, August 1988, pp. 50-59.
Finally, if China uses nukes on Taiwan, there will be two unfortunate results: Taiwan will use her own nukes in retaliation, and target those regions that give China profitable foreign exchange with the rest of the world (someone has calculated that China's entire foreign trade surplus is generated in a region the size of New Jersey), and the rest of the world will suddenly tell China "Tango Sierra, you brought it upon yourself."