To say the Arsenal will "fall apart" is Samir Nasri (or any single player) leaves might be over the moon. However, the Gunners can well find themselves fighting to earn even a Europa league spot with his departure. Why? The French midfielder's discontent reveals the effect of Arsenal's persistent underachievement for the past few years.
Arsene Wenger refuses to purchase good new players - particularly a holding midfielder or worker like Petit or Vieira. That is part of the problem. However, Arsenal's remaining players are good enough to keep them in the running. However, they are likely to remain also-rans if Nasri departs - if only because it's a consequence of Wenger's reluctance to develop a more resolute Arsenal squad.