the US will just incrementally move further and further right

This is just historically inaccurate. The US has been moving left (on average) since the late 1700s. The US was founded as a slave state in which property owning whites were the only ones who could vote for representatives and only representatives could elect the president. The US committed genocide against the native peoples and annexed territories by imperial conquest. There was no such thing as labor rights until the unions took them barely 100 years ago. We’re still making progress, but not without bumps along the way.

needs a healthy cleaning from the inside out

How?

Seems to me there’s 2 options, the constitutional way and the violent revolution way. So far in our history, the violent revolution way has been started quite a few times and it usually gets stamped out or enough concessions are given that it simmers down. Of course you can’t forget that the biggest one was an unsuccessful right wing revolution, better known as the Civil War.