If they win the FA Cup and squeeze in the top 4 - both long shots - and he stays then Arsenal will be just doing exactly what they have been doing over the last few years. From a United point of view, better that he stays. If I were an Arsenal fan, I'd be looking for him to gracefully but bearing in mind he doesn't deserve to be hounded out. Fergie knew when to call it quits at Man United, Wenger doesn't seem to have that awareness. It's sad from Arsenal point of view that his last few years might well be remembered for all the rancour and bitterness we have seen recently. Better to bow out when you know you have had your day and not overstay your welcome.
I think they have more chance of winning the Cup than top 4 though.