Humanity actually successfully implemented a decentralized egalitarian socialist society without dictatorships in 1936 Spain, which bore out that it's possible for us to achieve freedom for all while also ensuring everyone is able to live a fulfilling life by providing free housing, food, transportation and healthcare.

Some very specific outside circumstances caused it to be halted prematurely (namely, an unusual amount of industrialized fascist states and the USSR ganging up against it all at once, with very limited industrial capacity of their own to effectively fight back), but they documented how their society functioned while it existed quite well, and over 3 million people participated in it.

For most, is as difficult to imagine to an end to capitalism as it was for peasants to imagine an end to the divine right of kings, yet it did happen.

History shows us that we are capable of much better, and the global crisis we now face could very well be the catalyst that let's us end capitalism forever.

failing alien invasion or a mass extinction event

I have high hopes for a superintelligent AI takeover within our lifetime.

While perhaps not likely, there's a real chance that the AI could be a benevolent and fair ruler. And, if nothing else, being better than our current (actively malicious) rulers really isn't a very high bar to clear.

I think revolution can be accomplished without violence, at least until the ownership class resorts to violence to retain their wealth and power, at which point violence is thrust upon us.

As Nelson Mandela put it, A freedom fighter learns the hard way that it is the oppressor who defines the nature of the struggle,and the oppressed is often left no recourse but to use methods that mirror those of the oppressor. At a point, one can only fight fire with fire.

Although Elie Mystal noted if a Democratic triumvirate were to strip SCOTUS of jurisdiction (they can do that without a Constitutional amendment) then SCOTUS might declare that law unconstitutional (it's not, but this SCOTUS doesn't really care) and then we can have a situation where some states think the court's rulings are legit, while others think they're not, and states might be willing to go to war over it.

I'd love to see it but we are struggling to get enough people organized to take any action. It would take a large percentage of organized jurors to hold the courts hostage that way.

If we could get 5% of the population to just plum stop paying taxes, by comparison, that would force the state to the negotiating table. 3.5% participating in a general strike would do it as well.