I don't think it would be prudent for Arsenal to focus on only the premier league and not on the champions league. Arsenal is a big team and a big team fights for all the trophies available in the season. Focusing on one from the beginning of the season might be catastrophic because if they lose out on that one then they're left with nothing. Great importance should be placed on the major competitions which are the league and champions league. They can use the reserve team or second 11 to play competitions like the FA cup or caraboa cup if they're not facing a top opponents, but the champions league and League, should be their priority.
Finally, you'll find it hard to believe that Arsenal values the Carabao Cup Competition and also the FA Cup Competition more. I won't say they value it more than the Champions League Competition but they love these domestic cup Competitions. They've been poor when it comes to playing and fighting for the European Competitions or trophies. I'd say they should exert so much focus into winning the Premier League Competition next season.
It's cool for everyone to fight for the Champions League Competition, bit Mikel Arteta should also know that, winning trophies will obviously buy him time with thr club.
They're yet to sign a goalscoring striker. It's few weeks until the new season, I'm still anticipating who they've got in mind to bring into the club and squad.