Arteta showed the whole world that he knows what he is doing, and maybe they failed to win the title twice now, but they weren't even there before he joined so that means they are doing much better. When you finish a season sixth and fire the manager you do not realize how lucky you are to have a manager who came second and barely lost, because that is what Arsenal could have been right now.
Look at premier league, it is filled with a ton of teams who have a lot of money and a lot of talent and even a lot of history and yet none of them actually do better than Arsenal, just City that's it. So while it is sad to see Arsenal lose, it is a fact that they are doing much better than before and I think eventually they will get that title too.
I don't think Arsenal's opportunity right now is much worse (if at all worse) than Liverpool, United or Chelsea's. The other teams aren't even close due to sustainable financial development rules. For example, Newcastle cannot pour millions into the club even though they have money. Arsenal gains more points every season than in the previous season, that is, they are obviously progressing, but it is not clear whether this natural progress will be enough to surpass the cheating City.
I don't think, Arsenal performance will going to be worse next season, because we saw what they displayed in this season to ended up in second position, because their manager set a good plan for the team to achieve what they achieved in this season. You can see that new manager is about to take over from Liverpool manager and Chelsea too has replace their manager which is a sign that Arsenal will going to embrace a good opportunity to maintain that second position in the premier league competition. Don't forget that is not about the funds you use to sign players that will determine Newcastle united winning, because Manchester city still look like the team that will win this title again next season, because their players are still ready to do what they have never do before in any competitions.