I don't think this is state of the art. It's impressive, maybe, from a technical point of view given the massive constraints it runs under. It may compete with Unity or, to a lesser extent, Unreal on the low end. But there's lots of things you can do in Unity (which isn't really state of the art -- it lags behind the AAA engines in a lot of respects, although I don't know how much Unity 5 moved the ball forward there. This isn't to denigrate PlayCanvas, but it's not an open-source replacement for Unreal in the most typical Unreal Engine use-cases.
It's definitely state of the art. See our latest tech demo: http://seemore.playcanvas.com