I think Arsenal doesn't have to make a major overhaul to become champions because they already have a pretty solid squad and a good coach. At most, they only need to sign a few players who are really needed and don't have to make changes on a large scale. Arsenal's real problem is that they still don't have the winning mentality that Man City and Real Madrid currently have, and I think if on several occasions they can reach the final, it will form that necessary mentality on its own.
Arsenal is actually on a balance when it comes to squad. It won’t be bad if they want to add extra players to their squad but even with the current squad, they are very much solid to compete with top clubs. The problem I see with them is their relenting attitude when they’re suppose to put more pressure. They normally start very well with good energy but perhaps, the English media hype is one thing that deceive them thinking they have achieved much and begin to slow down their performance and end up losing important points.
Last season Arsenal were able to impress in the English league but in the Champions League they couldn't do much after being destroyed by Bayern Munich in the quarter-finals, to maintain or increase their potential to go far in the Champions League next season seems difficult to happen, because every strong team and even Madrid who won the Champions League last season are now starting to improve the team by bringing in new players, so there is no reason for Arsenal not to overhaul or improve the quality of their squad if they want to compete in champions league next season, although the current Arsenal squad looks balanced but you can see that the depth of the squad, especially their reserve squad is not qualified and it is very difficult for Arteta to maintain his team performance if later rotates when players are injured or absent in important matches, So it should be that Arsenal in addition to needing to improve their current squad mentality, of course Arsenal needs to bring in several new players to increase the depth of the squad they have.