Whether crude costs $60 or $120/bbl., the U.S. is almost free of depending on imported energy and positioned to supplant Saudi Arabia as the world’s top producer of oil, Citi's Ed Morse says. While U.S. producers break even with prices of $72-$75/bbl. and will keep drilling new shale wells at $60 because they’ve already hedged future output, the Saudis face different challenges.