1. No. Leftism/ Liberalism is capable of absorbing anything that could happen - not instantly, but over the space of not many days.
For instance it might have been expected that something as big as 9/11 would have made some difference of some kind to the trajectory of the USA - but the societal trend graph continues unabated, with only the slightest of wobbles perceptible in retrospect.
If not 9/11 - then nothing that happens could ever make any significant difference - certainly not the sheer insanity (lies, anti-truths, self-policed blindness) of everyday life in the public sphere.
2. Yes. If the Mass Media collapses for any reason - Political Correctness will collapse very quickly and very completely - because it is only the pervasive 24/7 influence of a Mass Media on a Mass Media-addicted population which enables the continuing insanity that is Left/ Liberalism.
And the Left are clearly not aware of this fact of their absolute dependence on the Mass Media - that it is actually the centre and source of modern Leftism - therefore the MM may well be destroyed (or rather, the chain-reacting process of destruction initiated) by Leftists, as a self-inflicted act.
3. Yes. Because - if such things were susceptible of quantitative measurement - it looks as if Left-Liberalism is an exponential process - and all exponential processes must stop: their very success is lethal to the prerequisites of that success.
And, when Leftism does stop expanding exponentially, Political Correctness will die; because it certainly seems to behave like the proverbial shark that must keep moving-forwards or die.
I should point-out that while I am 100 percent certain that Leftism is unsustainable, and will collapse very fully when the Mass Media collapses - I am not at all optimistic about the short to medium term consequences of that collapse.
In fact I am very pessimistic. Leftism has by now so thoroughly destroyed our social infrastructure, that the results of the collapse of Leftism are almost sure to be social chaos, disorganization and mutual predation in most places (as with the past 25 years of chaos in Russia) - and due to the unprecedented degree of economic inter-dependence, Western society is very brittle - damage will ramify very swiftly.
So: I have some Good News and some Bad News.
The Good News is that the people will, en masse, lose faith in Leftism very swiftly, very fully, very comprehensively.
The Bad News is that the post-PC population en masse are not likely to agree and cohere on anything much better than PC, indeed are likely to disagree about almost everything and (lacking a legitimate institutional basis) be unable to cooperate.
If you merely want to see the end of PC, then you can be optimistic that this will happen - maybe this afternoon or tomorrow, maybe this summer or in a decade or two - but for sure.
But if you want to live in a society better than this one, then you probably will not live long enough; and when the better society eventually arrives, there may not be many people remaining on earth to enjoy it.