I don't have a high opinion of my musical abilities :), but I agree that catching-up is both a doable and daunting process.
But, finding niches of interest to focus on usually helps, as it does when crafting really good songs in a specific style, one that matches your musical abilities and understanding. You may not have the chops, but you can still create amazing work.
With programming, I have the issue of wanting to catch up on everything and do side-projects (eventually, I'll run through this class => http://faculty.cs.byu.edu/~jay/courses/2012/fall/330/course/...), but I have found success in trying to pick-up things in conjunction with a task at hand. If I have to build a web service, I'll start that research simultaneously. Starting IOS work... then spend time with C, understand Objective-C's runtime, read about the history (and play around with Smalltalk). This piece-meal approach seems to make the jump more "doable" in my opinion.
I think that people without a CS degree can obtain a good, challenging gig if they have a good niche to school themselves in, and of course, pick-up the gaps from the people they work along with who have that background/knowledge.
As a person with a masters in music, a bachelor in film, and now programming for a living, I def. believe that having a persistant interest in learning about those "fundamental software concepts" is what makes such a gig achievable, especially if you keep doing the extra work in your spare time (like taking Dan Grossman's unbelievable Programming Languages class or going through Zed's LCTHW).