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.
Maybe this is the one area where Arsenal can be relied upon to finish runners-up in the Premier League. This team also drew with Premier League champions Liverpool a few days ago, in which both teams managed to score two goals each. Arsenal will still play two matches against Newcastle, one of which is a Premier League match and the other is a club friendly match. However the most important match between these two matches will be the Premier League match because through that match, Arsenal may have another chance to become runners-up.