

The USA under Trump wants to make being an empire worth it financially while getting some territorial gains.
Greenland could be a second Alaska for the USA as Greenland has untapped mineral reserves and a strategic location in the Arctic Circle. Annexing Canada would be on par with the Louisiana Purchase or gains from the Mexican-American War. Panama is a major strategic asset.
Trump wants to leave Europe because he doesn’t see anything for him by staying.
I don’t think it would.
First, you’d have to power the device, which is likely going to take a lot of energy.
Second, the device is additive only, so it can’t address issues with built in scarcity like land.
Third, there is going to be an interesting middle ground where you still need some forms of manufacturing to run the economy.
There will be drastic changes to the economy, but I doubt that communism would fully take over.