According to Jamie Sanderson, Arsene Wenger plans to have a sit-down meeting with midfielder Alex Song to discuss his future at Arsenal, in the face of speculation that Song could follow Robin van Persie out the door with a move to Barcelona. Meanwhile, Arsenal are preparing to move for a replacement for Song, if he is allowed to leave. According to Sky Sports, Lucas Biglia is one possible replacement, as they claim that Arsenal lead the pack trying to sign the Argentine from Anderlecht.
One way or the other, Arsenal do not intend to be left with a lack of experience at the most defensive of the team's three midfield slots.
It appears that neither Wenger nor Song particularly want the player to be sold, but the source of the issue is Song's agent, who has been floating his name to several foreign clubs. Arsenal plans (or planned) to open negotiations with Song over a new contract, even though his current one still has three years left. However, Wenger now wants to ensure that Song plans to stay for the long-term before negotiating, or else he will be sold.
Arsenal refuse to let him move for a cut rate, but it seems that Barcelona are at least one club that are willing to negotiate, so it's clear that Alex Song may be on the move. If he doesn't commit to Arsenal in his meeting with Wenger, he will likely be sold.
Meanwhile, the search for a replacement, if necessary, has already begun. Rumors of Arsenal's search for a defensive-minded midfielder have existed for months, but Sanderson says there is a "dossier" on several possibilities, including Yann M'Vila, Etienne Capoue, Victor Wanyama, Kara Mbodj, and Lucas Biglia. Furthermore, Sky's Graeme Bailey says that Arsenal are the frontrunners for Biglia, as Wenger has long valued him even as Real Madrid and Inter Milan have shown interest.
I put a lot more stock into Sanderson's reporting than Bailey's. The Sky report features the ever-popular "Sky Sports understands," and the sourcing is unclear. It's likely that Arsenal are interested and possible that they are the frontrunners, but I wouldn't get too excited yet. It is, however, reassuring to hear that if Song does move (and even that is not definite), contingencies are in place to cover for his absence.