If the current NFL referees do not come to terms with the league like the players did roughly a year ago, there could be a huge problem for the 2012 regular season. According to the league, negotiations are at a standstill and the plan is to begin training replacement refs starting immediately. In a sport as fast and violent as professional football, the official's impact can have a huge effect on the outcome of a game.
SB Nation has been on top of this issue since it originally broke. A story by Joel Thorman titled, "Replacement Refs In NFL Are Disaster Waiting To Happen," surmises that there placements would be retired college refs and Arena football officials, but not current college football refs, who wouldn't be willing to risk losing their college gigs when the "real" refs finally settle.
The story goes on to predict that the league and officials union will settle in time for the season to begin on schedule with the regular refs and this is more like a bargaining leverage ploy than a legitimate threat. SB Nation has a full story stream with all the updates on this continuing issue.