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.
No matter about Arsenal who managed to improve the quality of the team because anyway, Arsenal will only focus on the Premier League and not for the Champion League. Because anyway, that Arsenal are also not too often able to play in the Champion League but indeed, in the last season also at least Arsenal managed to qualify for the quarter-finals but unfortunately, Arsenal lost by Bayern Munich.
But in my personal view, that is still not enough to say Arsenal are strong in the Champions League next season. Although indeed, Arsenal have bought players and or have had good performance, but I believe Arsenal are still not strong enough if they have to compete in the Champion League. Maybe it can be concluded as well as Milan in Serie A who managed to become a team in the Scudetto competition, but in reality they are still weak for competition in the Champions League.