#1 Success is more of a Journey
Even if Arsenal sack the French boss with immediate effect, it would not assure any instant success to the club. It would certainly be hard to fill in for the longest-serving manager in the Premier League with an unmatched experience.
When Sir Alex left United, the club had a shambolic spell of three years and only showed signs of recovery under Jose Mourinho in 2016/17. Similarly, Liverpool were never playing with such flair under Klopp - until the 2017/18 season - where they are ripping defences apart on their will.
Wenger parting ways with Arsenal would start a rehabilitation process for the club which could eventually lead them to glory in the forthcoming years. The start, however, needs to be made now.
The success is more of a journey than a destination. A new manager at Emirates would bring in a new philosphy, a new set of players, coaching staff and much more. It will take time before getting used to the changes at the club.
Thus, Arsenal would not be recovering anytime soon even if they sack Wenger today.