Okay maybe not that much 
I get that Arsenal is doing awesome this year, and they are quite hyped, but I would say maybe a few players missing would be the best they could do.
Their biggest advantage is that other teams in the premier league that are their rivals for the title plays in UCL and care about UCL a lot more, City would want to win UCL more than winning EPL for example, whereas Arsenal would be happy to get Europa, but would prefer to get EPL instead, and that is why they will play their best 11 on EPL, whereas City would play the best on UCL, and this is why we could maybe see a shocking loss from Arsenal on Europa time to time, maybe even eliminated.
I get that Arsenal is doing awesome this year, and they are quite hyped, but I would say maybe a few players missing would be the best they could do.Their biggest advantage is that other teams in the premier league that are their rivals for the title plays in UCL and care about UCL a lot more, City would want to win UCL more than winning EPL for example, whereas Arsenal would be happy to get Europa, but would prefer to get EPL instead, and that is why they will play their best 11 on EPL, whereas City would play the best on UCL, and this is why we could maybe see a shocking loss from Arsenal on Europa time to time, maybe even eliminated.
The Gunners are one of my favorite teams since the days of Thierry Henry, Dennis Bergkamp, Robert Pires, Freddie Ljungberg and no stranger to us, the professor Arsene Wenger. This season, I have enjoyed their style of play under Mikel Arteta. however, if I read your post.
hmm, the analysis is quite reasonable, some of the points you say are quite representative of the actual situation. however, that doesn't mean that because Manchester City care more about the Champions League, they will automatically ignore the domestic league competition.
because after all, they will make sure to secure their place in the domestic league. after that, they can concentrate more on the champions league.
As for the Gunners, we agree, they will prioritize the domestic league over the Europa league. there are several factors that cause them to slip up, they don't have enough second-tier players, but that doesn't mean they aren't targeting this competition.
after all they are one of the strong teams in the Europa league competition.