quite simply i don't think there are managers actually available (as in not working) to take his place right now and give the season some respectability.
there will be some currently in work that would come here if we pulled the trigger on wenger now but then it becomes a question of how long do we want to keep them, when far better options may be available in the summer? managers will hop in and out of chelsea for now because of the pay off, very good players and chances to play near the elite but a short term role with us isn't so attractive.