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 are not missing out on anything not to be a major contender of the champions league just like Manchester City and Real Madrid have been over the years now. Arsenal are a great team and they have all it takes to win any trophy now. Just like you’ve mentioned, they just lack that winning mentality and that is what have caused them to not have win any trophy for themself till date despite the great performance they pull up every season. If they can have that winning mentality and their mind set at making sure that they get what they want by all means, they can win a trophy in the next season. I have so much believe in them but they always disappointed towards the end of the season.
What do you mean always? How did they disappoint last season when they struggled all the way up the league? And it wasn't just Arsenal who made mistakes, but Liverpool and also Manchester City, who went on to win the league. During the season it is very difficult not to make any mistakes, especially when you have to play not only in your league, but also in the Champions League, which has a completely different style of play and mentality, including the domestic cup, it's not easy. I was surprised that they lost to Bayern with such a minimal score, because the tension during the season for Arsenal was such that they could have easily conceded more in this match, but no, they stood up honourably