There is, but it isn’t trivial. For starters, a lot of additional CSS codes would be needed, and figuring them out is not trivial either. Because the theme relies on a grid system, that grid system itself will need to be changed. That will probably break a lot of things, so you’ll have to go in and find what’s broken and fix them by adding appropriate CSS codes.
Moreover, there are also other not-so-obvious pieces of codes that relies on the width of the theme. For example, if you auto-embed videos into any post or page, you’ll see that the video is always resized to properly fit the available content area, regardless of your column width settings.
To be honest, things like this will be very difficult to implement and maintain at this far along point of the theme’s development. If we were to begin from scratch, then yes, we could start with fluid width from day one.