Failed

I've been teaching myself everything I needed to know in order to conduct business online for the past 12 years. I decided to go back to school and I'm about to start my second semester as a web development major. It's a breeze, I'm just relearning things I know and have forgot, improving techniques, and finding out better ways to do things. But, as I browse through my course schedule I found myself wondering if it's the right move, to take subjects that I already have a strong knowledge of just for the credits, or should I move into a new major, mobile application development?

What do you all think? Obviously mobile is booming, and will continue to grow. Is this the perfect time to change my major and get into the mobile field? Or stay with what I know and improve my skills?

I would appreciate your thoughts!