Had he refused to step down I strongly suspect that he'd have been forced too.
Clearly the sweeping changes behind the scenes last summer were all part of a plan. Arsene was handed a two year deal to oversee the transitional phase (hence him saying that his position would be reviewed this summer when he signed the thing).
No as he is (correctly) a manager who has total faith in his beliefs and ability and I am sure he would have been confident for next season given the introduction in January of two top level players and the assorted cast he already had in place. Factor in 2-3 perhaps new players in the summer and call me naïve but there is grounds for optimism.
Club was clearly working to this with the appointments of the scruffy German and others. Perhaps the travails of this season have just forced their hand – or perhaps their number one target is now available and it is time to act.