I also see Arsenal as a team that can still be quite strong next season so that some of their closest rivals last season also still have to be wary of Arsenal as their competitor in the race for the Premier League trophy. Likewise in the Champions League because Arsenal could perform better next season and be able to reach a quite crucial stage so that their rivals will still see Arsenal as an opponent that needs to be eliminated early before heading to the quite crucial stages in the Champions League.
Arsenal are still very much a contender for the premier league title and all teams needs to be wary of them, i believe they would be better prepared than last season. It was unfortunate for them not to have won the league but they gave it their best shot, if they get a better striker i believe they should be able to challenge better than before. For the Champions League i believe they lacked experience that was why they lost, most of the players haven’t had any champions league experience last season but this coming season they would perform even better.
I don't think any team is afraid or worried about Arsenal's presence and in fact other strong teams are wary of teams full of history who have always been regular champions of the league. Maybe Arsenal is very scary for any team in the same group but after that they are nothing more than a team that can be knocked out easily.
This is funny but you said the fact, Arsenal are still lacking in experience to challenge stronger teams and most teams frequently play in the Champions League have more threat than Arsenal but in a few years they would also get to that level if they are able to maintain their performance and qualify for the champions league every year.
That's the moment when I realize that some people on this forum are delusional about some clubs and possible performances in the toughest league in the world. Arsenal finished the season with 89 points and a winning streak of 6 games! Is that what you call "mess up"? In my opinion it is remarkable how they played last season once again, but as we all know there is a team in the Premier League that can step up their game any moment when necessary and that is Manchester City. That is what they are doing without mercy. 89 points is a strong result. But it is not enough.
If you don’t want to be sentimental as a fan what happened to Arsenal last season was really embarrassing and everyone expected them to have learned from their mistake in the previous season. Losing a crucial match woefully against Aston Villa was the mistake that Manchester City capitalized on to win the title such mistakes should’ve been avoided especially towards the end of the season. Looking at the situation i will also say they Messed up because the whole outstanding performance all amount to nothing.