How can you seriously be unhappy with top 4? We obviously won't compete with City or United because they can spend vastly more money than us. We need to be happy with the best we can realistically achieve.
Also, Sanchez won't leave. Wenger has been very clear on this on multiple occasions. Think how silly he'd look if he let him go after saying 4/5 times that he will definitely, without a doubt be an Arsenal player this season.