Subversion was (and is) an admirable project, and filled a void by being much better than CVS.

When I discovered git, I couldn't go back to svn - git fit my mind _so_ much better.

It might not have seen the meteoric rise without GitHub, but just like it's weird to find servers running an OS other than Linux these years, I suspect there would have been a steady growth that eventually made it dominant.

I suspect it will be very hard to unseat git at this point - for all its untuitive UI it's good enough for most things, and it's been slowly improving for the use cases where it's weak.