What does it look like to live in a post-Constitutional-Republic society? What's so different say, in Hungary or Poland, or the Philippines, now that there really isn't much question about it being authoritarian? Same with Russia.
I mean, Russians still go to work, make stuff in factories, drive cars around. Lots of Russian young women making a living on the internet it would seem. Putin doesn't necessarily go around killing them all at random.
Saudi Arabia's an authoritarian regime of a different stripe - but most of the citizens there just go about their lives. They're not always ending up getting tortured in awful prisons, but instead probably work in their businesses, look after their families, and die of old age. The same's true of Iran. And China.
There's a big part of American society that will just carry on as normal, if your Republic dies. And your trading relationships with the rest of the world will carry on just like China's or Saudi Arabia's do, except with a bit more graft than before. A bit less safety in working conditions, or responsiveness to environmental disasters etc. But y'know, even Chernobyl was sorta managed by the Russians when they were the USSR, and is still, sorta.
How would your life be different as an average American citizen, if you do transition into authoritarianism? Would it really matter if you no longer got a meaningful voice in your own government - considering that across history most citizens have never had one?