Anti-war means anti-capitalist. They’d be happy with a leftist US.
You need to look deeper into these groups. At their core they are full fleged communists and anarchist-socialists. They want to tear down our Constitutional form of government.
Have fun thumbing through their litter-ature...
http://www.akpress.org/
Ted Rall is in this movement. It is why he supports the right to bear arms, he wants to have a gun with the revolution begins.
There is no US in their worldview. It would cease to exist. Would it merge with Canada and Mexico? Who knows.
The constitutional form of government we have would be overthrown. With that, the constitution itself.
That is no "leftist US" any more than independent Russia, Ukraine, Poland, etc. are still the USSR.