I think this is the right momentum for Arsenal to be able to compete again for the title, Indeed the victory against Manchester City was only one match but this had a big impact on the mentality of the players so that they could be even more enthusiastic about the match.
On the other hand, facing Chelsea at this time will be another challenge even though there are still many who doubt Chelsea now but with their successive wins and the new formation with 3 strikers it makes them a little different and quite worthy of being wary of later.
Sterling's movement on the wing is quite troublesome and it is Arteta's job to find ways to reduce this player so that he is not as comfortable on the field.
All Arsenal has to do is to be consistent. Beating Manchester City would become meaningless if the next few coming game weeks they lost points to other low league sides. This is exactly what happened last season. They started losing points to weaker teams where it mattered most, and before we realized it, Manchester City leapfrogged them and won the title.
We still have a long way to go through the season and a lot of things could happen, especially with player form, how deep the squad is and injuries to different players.
This is going to be difficult because when you look at Arsenal's form they've been very good at times but taken a turn for the worse in some unpredictable games so this consistency is going to be very important and it would be great if they paid attention to this.
Arteta sometimes finds it difficult to maintain their consistency which is something that is very important to do because if not then this will hinder their journey (back) but indeed even though this match against Manchester City is only one match it would be great if they are more motivated by this victory and use this as their momentum to make some good changes at the beginning of this season.