Arsenal is a very good team and I agree with you that they will be able to have an excellent run in the champion league considering the fact that they have made some excellent signings and above all Jorginho has signed the renewal of his contract with Arsenal which personally is a a player who I like very much even if he didn't shine in these European games with Italy but he will have time to make up for it on the big stages
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.
In the domestic league, maybe Arsenal should be taken into account in the competition for the championship trophy, but sorry, I think Arsenal is still not able to compete in the Champions League because the mentality they have is still far from other teams in the Champions League so far, we can compare last season how they also failed to give a lot of resistance to Munich even though at that time Munich was in bad condition, next season the Champions League will use a new format in the competition and it allows many teams to participate in the Champions League next season so indirectly making Arsenal chances to go further in the Champions League very unlikely to happen, the mentality possessed by the Arsenal players is very bad when they have to face an important match and they should be able to win in the match but in fact they often slip in the match the important match.