Schneider, a 16-year NHL veteran, won't be able to play due to his unresolved contract negotations with the Detroit Red Wings. A member of the U.S.'s World Cup-winning team in 1996, Schneider was named to the original Team USA roster on May 20.
"Mathieu has informed us that, due to his unsettled contract situation, he has regretfully withdrawn from competing in the World Cup of Hockey," Team USA general manager Larry Pleau said. "We are disappointed that he will be unable to participate, but at the same time excited to add Hal's unique skills, physical presence on defense and recent international experience to our lineup."
Gill recorded two goals and seven assists while playing all 82 games last season for the Bruins. He played for Team USA in the 2000, 2001 and 2004 World Championships, helping the U.S. win the bronze medal last May in the Czech Republic. In nine games, Gill had two assists and 12 penalty minutes.
Team USA will begin its training camp on August 20 in Columbus, Ohio. The World Cup will be held from Aug. 30 to Sept. 14 across North America and Europe.