I would expect they follow the model many other open source companies have done (deviations from this would probably raise at least one of my eyebrows): services and support.
I've run CM on most of my Android devices at some point. I stay with the vanilla carrier OS for a bit, but it inevitably starts to annoy me, and generally ceases to get updated after a year or two.
The dev community has done a terrific job of making it easy to root and install CM on a wide variety of phones, but everything still comes with massive "if you brick your phone, don't come cry to us" disclaimers all over it. This limits the user base to people that are comfortable hacking around on a command line and are okay with a small chance of owning a $200+ paper weight. Offering support contracts such that the average person doesn't have to dig around for hours on xdadev and cm forums trying to find information when they run into problems would expand their potential user base and be a welcome tool even for us hacker types. I know I've spent way too long trying to get S-off on my HTC One X. None of the wikis or forum posts have offered anything that helps resolve my specific issue. I'd gladly spend a bit of money to have a dedicated support person help debug it with me. Somebody who understands how the exploit works in detail and knows what and where to check to figure out why my phone in particular isn't working. I'm confident I'll eventually figure it out, but it's taking a lot more time than I'd rather spend on it.
They also currently provide premium services like an app that enables OTA updates to any CM rom, automated backup utilities for recovery, themes, launcher apps, etc. There's a lot of potential here for offering paid services that take advantage of your additional capabilities having an open phone.