Arsenal are in range of Newcastle and City at the moment so I wouldn't say they are safe and they have lost 3 of their last 5 games and drawn 2 in all competitions and their next game is against Newcastle and if they lose they can get past them. But I don't think it matters other than the money for a place in the Premier League, there is a winner and that's all that matters, everything else is just statistics.
Arsenal only needs to beat Newcastle to settle their runner up status in the Premier League, tough to settle the scores in as much it will be hard on both teams i believe in Arteta and his team will be controlling and winning the game, it is aswell to be played at the Emirates, the home of Arsenal if 3 points should be given to any side Newcastle are not going back with the 3 points. Arsenal last game will be against Southampton, another 3 points for Arsenal, irrespective of what they did to Man City now that Arsenal are in better form.