Will this be github's answer to layervault?
I'm not sure it'll be a complete, or design-focused replacement.
This said, GitHub have been very good at maintaining a smart choice of features on top of git's core. That makes me believe some improved design files support could be in their plans.
There are already some simple image diff tools in github's UI, hopefully they'll expand support for more complex file formats like Photoshop and Sketch files. Or launch a designer friendly environment for this type of usage.
One one hand I'd say yes, on the other it's not realistic to expect most designers to use git from the command line. LayerVault's feature set was a lot better, but I think the real advantage it had was an easy GUI.
Once Github adds storage amounts to their plans this should be a great opportunity for someone to build a really nice desktop app that takes advantage of this feature.
Looks extremely useful; for (large) resource files or binaries. Nice move Github!