I'm going to be somewhat surprised if he doesn't get re-elected, although you can chalk some of that up to my pessimism about human nature. Authoritarians have been in charge for as long as we have recorded history; democracies are a statistical anomaly, and we're much too violent and nearsighted a species to really be able to make any of this work. If it's not Trump, it's going to be someone or something else. If anthropogenic climate change isn't "it", we have the capacity to fuck ourselves over in so many different ways that it's only a matter of time until the human population gets dramatically reduced
In the the American system of checks and balances was supposed to take advantage of people's proclivity towards selfishness. They figured that it would work, because everyone would want to flex their muscle. That's what power hungry people usually do. Unfortunately, nobody even envisioned a system in which Congress just lays down at the feet of the president, to pretend like they work for him. I thin that Trump will lose, but I think your broader point is probably correct. Eventually the system will fail.
Considering how popular far right parties and sentiments are over here in Europe, I'm honestly a bit scared about what's to come – and more than a bit pessimistic considering the current trend. But yeah, the US really isn't doing too well right now either. Bit of a global clusterfuck, really, considering the pandemic and all.