Arsenal are stuck as long as Wenger is around. Once Wenger leaves and they get a top manager in who could add some steel to them, they will be back in the 'bigger' teams category.
Under Wenger though, Arsenal are not going to win the league in all likelihood. Wenger is the finest collector of springboards known to football. He collects spring boards and then never uses them to spring board to bigger things.
What do I mean, well UCL football is a spring board to challenge for the league. Wenger had it for years and never used it. 3 FA Cups in 4 years you would think he would use that to spring board to bigger things but nah.
However to be fair to him it was he who made Arsenal a big team but of course he doesn't have a right to stop the club's development into 21st century football club. Football has changed and Wenger can't keep up.
Arsenal's board are too much of a coward to sack him and he is too stubborn to see that he is failing the club and step down.
Arsenal remain a 'big' team. Their problem is that there are now other big and bigger teams which was not the case 15-20 years ago when Wenger was enjoying his honeymoon.