Joint Sunday editions of The Detroit News and the Detroit Free Press will come to an end with the sale of the two newspapers to new owners. The Free Press, formerly owned by Knight Ridder, was sold to Gannett Co., the nation's largest newspaper chain. The News, formerly published by Gannett, was sold to MediaNews Group, a Denver-based publisher. "What it will mean eventually for this market is hard to conclude," said Ben Burns, director of the Wayne State journalism program.