GitHub has to have revenue to continue to operate. I'd rather GitHub go down the road of enterprise and other paid contracts, rather than going down the road of becoming SourceForge and all the ickiness that that entailed.
They have revenue and are cash-flow positive. Their problem is that they aren't profitable enough to give good returns on the investments made in them, not that they're in any danger of going out of business.
I wish they would be happy to service accounts like mine at $100/month. I prune all the time to stay on my grandfathered plan and not get bumped to $300/month. That said, we are moving most of our private repos which do not require outside collaborators to our self-hosted gitlab. Bonus -- gitlab comes with CI! -- another product I can skip paying XXX/month for. Lest you think we free ride, we've made substantial contributions to gitlab through our paid open source internships.
Thanks for contributing to GitLab. Glad to hear you like CI