I think that win by Arsenal over Manchester City in Emirates could be an indicator of a thing for this season. I mean Arsenal might maintain the title competition until the final week this time. You know how they fought for it last season for a long time. However they started a really bad streak on the final weeks which eased Manchester City's job a lot.
This time Arsenal seem even more dedicated at least for now. Winning against Manchester City in a big game isn't easy normally.
Arsenal is no doubt a title contender but it's too early to see them as a favourite just because they won Manchester City, the defending champion. The league has just started, there's going to be more games to be played, there's going to be injury worries and a manager ability to keep his team fit will determine how far they will go. Last season, at some point the team became fatigued and most persons claimed that Arsenal's lack of depth cost them the EPL trophy. Arsenal might make same mistake again or it could be that Mikel Arteta has learnt his mistakes, but very soon time will tell.
You are completely right, I myself was among those who expected Arsenal to in the EPL trophy last season, but unfortunately, just as yo have said, just towards the end of the season, when they were expected to play even better than they have played since the beginning of the last season, I personally can not tell what actually happened to them, whether fatigue, or they become too overwhelmed, I cant say, all I know was that they started losing and drawing games which ordinarily, they should win easily. This indeed at the end of the season cost them the EPL trophy.
Personally though, i will want to believe that not just the manager/coach of the team, but the entire team as a whole must have learnt from that mistake, and are well prepared to make sure the same does not repeat itself again this season.
And yes, it is too early to begin to see Arsenal as the favorite team in the season, there are still a lot of games to be played just as you have said, but then, i hope Arsenal will continue to give us a good game play going even further to the end of the season.