There are decades and centuries where authoritarians and dictators prevail. There is no timeline for guaranteeing democracy and human rights will prevail.
It takes action, diligence, and sacrifice to preserve those things. And even more to regain them once lost.
Of course it eventually falls down, everything does. I'm not saying it won't be difficult, nor many people will ultimately die, and the country will be very different. But it will happen, if not sooner, then later, like in every other place in the world.
By defintion, if it “never fell”, it would be one of the authoritarian states we have today, so the obvious lack of any example fulfilling that criteria doesn't demonstrate anything one way or the other.
Now, if you could say something like “point to any authoritarian regime existing after <year> that had existed for longer than <span in years>”, that might tend to support the claim that, at least after a certain point in time, authoritarian regimes tended to have a particular finite lifespan (of course, you can never prove that currently-existing regimes aren’t exceptions to that withot access to future knowledge.)
At one point I had a hypothesis based on a few notable examples that with certain definitional bounds this might work with some point in the 20th century and about 80 years (even had a bit of process explanation, though not a strong theory on why it didn't apply earlier beyond the general spread of democratic ideals) but I never rigourously checked if there might be exceptions.
(Of course, plenty of authoritarian regimes fall only to be replaced by different authoritarian regimes, too.)
Because you didn't end your sentence with "Plenty of autocracies last forever" but instead you gave them a duration. Maybe that duration sounds long, but it ends eventually, which is exactly my point.
Think more of the earlier end of medieval era, where the peasant class was mostly incapable against feudal armies, even in many cases with massive numbers on their side.
There’s an entire surveillance state, eyes everywhere, gait recognition, massive intelligence networks all at a scale unimaginable by kings and dictators of the past.
I wouldn't be so pessimistic! The inevitable swing towards authoritarianism in the US happened much sooner than I expected, which also means it'll swing back again much sooner too, likely to be way before 2060. I'll throw out a prediction and say that the soon-to-be-authoritarian state that is under construction right now might fall as soon as 2035-2040, and it'll be a wild swing the other way once it happens.