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.