Jake Lamar does not claim to be clairvoyant. However, with his first novel, “The Last Integrationist,” Lamar has created a work that is not only humorous and richly written but may also prove to be a literary forecast for the United States. “The Last Integrationist” is set, as Lamar puts it, in a “virtual America. It’s sort of an America that you recognize. It’s not quite what America is today, but what it could be. I wanted it to feel like it was just around the corner.”