The German centre-back was a near certainty to leave under Unai Emery, but he has improved under Mikel Arteta.
While Mustafi is not immune to the odd howler, he has become a valuable part of the Gunners rearguard under the young Spanish boss.
And he admits he may stay beyond this campaign.
"I have always taken things day by day.
"We had a game on Thursday, we have the next important game at the weekend and as long as I am playing for a club — it doesn't matter which one, I play now for Arsenal and played before for previous ones — I always give everything until the last minute.
"When I decide, or when the club and I decide, it is going to continue, I am happy to continue.
"If not, then we have to go forward."