If the National Hockey League and its players union fail to reach a new labor agreement and avoid a lockout, NBC could be scrambling for a replacement for one of the linchpins of NBC Sports programming. NBC signed a $2 billion, 10-year contract with the NHL last year. Any delay in the upcoming season would stall any momentum the network established with the London Olympics. Talks between the NHL and players union broke down last week over economic issues such as revenue sharing. Team owners owners have threatened to lock out players if they don’t have a deal by September 15. As of this afternoon, Reuters reported that talks between the two sides had not resumed. Comcast was counting on hockey to strengthen its NBC Sports Network. A lockout would result in major holes to fill in the fledgling network’s prime-time lineup.