Arsenal are going to go again for the Tittle charge this season,and despite not placing them as the favourite,they are still doing their thing,and they will continue to do their best whether people believe in them or not.I know they dissappointed a lot of people last season,but it isn't a problem,they can go on to win this league this season,I am not very optimistic about that,but they have improved in a lot of areas this season.
If Arsenal do not win the league this season,I am sure it might be some other team and not Manchester City.
City have tried,winning the tittle back to back,and I'm sure they won't allow that happen again,some other team will snatch it from them now.
Well like I said earlier I'm not going to crown any team the Champions yet until it's a game or 2 games to the end of the league, because I don't want to be disappointed like last season, we'll Arsenal are in good shape currently they might be doing their thing like you said but do not forget that just like last season they could drop points as well, they might not win the league but I'm pretty sure they'll still finish top four.
Also note that they're still other clubs that are performing very brilliantly as Arsenal this season and could give them a very good competition, the likes of Tottenham, Liverpool and even Manchester City shouldn't be written off despite the fact that arsenal win the recently, they're the title defenders and got high chances of winning the league again, however it won't come easily and they'll definitely face more challenges this season.