1) Joel Kotkin predicts that the US population will reach 400 million by 2050, an increase of 100 million from current levels. He believes population growth will be driven by diversity and filling of currently unpopulated areas of the heartland. 2) Parag Khanna argues that countries interact in dynamic ways beyond static geopolitical borders. He cites the EU as blurring boundaries between nations and sees Russia as exemplifying this 'second world' of countries between first and third worlds. 3) Both authors provide credible analyses by drawing on knowledge of history, current trends, and reasonable projections, with Kotkin being an experienced demographer and Khanna exemplifying borderless interaction through his own background.