I think people tend to conflate git and the hosted services that became popular around the same time. Some people literally think git===github. Git popularised a style of workflow with rapid, cheap branching and collaboration as a first-class citizen. From a technical point of view SVN probably could have powered the same thing, but it didn't at the critical moment when git became the new and shiny. From what I've read it quickly played catch-up feature-wise but it never got people back once they'd switched.
I've no doubt something will come along and blow git out of the water... just as it did to svn... and svn did to its predecessors... and so on :)