With a colonial state like America you can't just replace it's power structures with communist ones, because those power structures are so ingrained with America's existence. Replacing the power structures necessitates a complete tear down and rebuild of political, social, economic, and even physical structures across the country, along with renegotiating use of the land with the native population (which they have every right to just kick everyone off). Whatever's left in its place after the region currently known as the USA transitions to communism will be utterly unrecognisable as the America we know today.