Before his introduction, Liverpool had a massive deficiency in quality. From 2016 to 2020, just seven of those 37 players are still at the club. That is the kind of overhaul Arsenal will need for the future, and there's hope.
Arsenal are currently in 9th place, much like Liverpool finished in 8th place four years ago. That means no European football to worry about, which means no more Thursday night games. That means Arteta will get a full season of just domestic football to shape the team in his style while signing the kind of players necessary to bring Arsenal back to the glory days.
Only time will tell, but my prediction is that Arsenal will have either won a Premier League or Champions League trophy by 2023.