[...]Bruce Sterling calls them “the Stacks”: Amazon, Apple, Facebook, Google, Microsoft, [GitHub].
They don’t want much, those Stacks. Just your identity, your allegiance, and all of your data. Just to be your sole provider of messaging, media, merchandise, and metadata. Just to take part in as much of your online existence as they possibly can, and maybe to one day mediate your every interaction with the world around you, online or off.
It’s very convenient to live in a Stack. It’s easy, it’s seamless, it’s comfortable. And it means putting much, or very nearly all, of our increasingly important online existences into the hands of a few titanic megacorporations. It means relying on their benevolence, not just today, but for the foreseeable future.
At the same time the secret to Github's success in my opinion is all of you hackers who use it to collaborate, not their genius business model or anything like that.
When git was gaining traction they were quickest to pivot that way because, well, they had nothing to pivot away from. The real test IMO with only come when the git-killer scm tool starts to take off; if they can keep their market share at that point then I'll be really impressed.
Now git has its own weaknesses with large objects, steep learning curve and complex UI, and difficulty of central control. But the difference is that those things are all the result of tradeoffs which make git very very good for the most talented programmers, and open source in particular. You're not going to magically make something that solves all those problems but still is as good as git for versioning the average small to medium open source software project.
But even if you do, will it be good enough to convince the greybeards to switch? Did Sublime kill vim? I actually think that whatever kills GitHub will not be the same thing that kills git. It will probably be a convergence of trends that remains unforeseeable for the time being, much in the same way that GitHub rode a series of trends which would have been utterly unpredictable 10 years ago.
While GitHub has obviously spent enormous resources around hosting git repos there is nothing tying them to git as an SCM. If for some reason Mecurial or something brand new becomes the new hotness GitHub would be able to accommodate. Their business strength is around the community and users, who they seem to keep happy.
It's possible that git also is fundamentally flawed in a way that some genius will reveal down the line, but I'm just sticking my neck out my neck like so many futurists before me and say that I don't see it as likely.