Yeah, the FA Cup is Arsenal's biggest chance of winning something. Sure there are some good teams left in the cup, but in Champions League you have Real, Barcelona and Bayern Munich for example, not exactly easy.
Arsenal really have to do something during the summer, but honestly I feel with Wenger. He obviously has tied hands from the board, and I don't think Arsenal has the amount of cash to buy players for, that Wenger wants us to think. In the past he had no problems with buying players, so I don't think it changed just all of a sudden. They wanted Benzema and Mata during the summer, were close on Mata, but when they couldn't get up the cash, he went to Chelsea instead.
It's also very noticeable how much they miss Wilshere. I like Ramsey myself, but if you look at Ramsey, Arteta and Rosicky, neither of them are looking into really moving forward with the ball, it's often passing sideways.