I guess stranger things could happen than the U.S. purchasing Greenland from Norway.
After all, the U.S. Virgin Islands consists of the main islands of Saint Croix, Saint John, and Saint Thomas, and many other surrounding minor islands. The total land area of the territory is 133.73 square miles (346.36 km2). Previously known as the Danish West Indies of the Kingdom of Denmark–Norway, they were sold to the United States by Denmark in the Treaty of the Danish West Indies of 1917.
So I guess if it happened once, it might happen again.
What might motivate such a proposal. Perhaps it is financial.
Steve Keen, professor of economics at Kingston University, London. Keen was one of the few economists who predicted the international financial crisis in 2007 – 2008. Now he has quite gloomy forecasts for both Norway and the rest of the world. Soon, there will be new recession, said Professor Steve Keen to NRK. The sky-high private housing debt in Norway is alarming and might be the trigger of a new crisis, according to Keen.
Greenland is rich in natural resources especially in rare earths metals which are needed to grow the tools of modern technology. It may also be a strategic military asset. The U.S. could grow its tourist industry. There are probably many ways it could benefit linking up with the U.S.