We have featured SVG native rendering in core for a while now, but because of WMF specifics, it has so far not been used by default. The third parties have indicated on multiple occasions that browser support has progressed to a point that they want to see it enabled by default, so that they do not have to handle the thumb nailing for it any longer.
Let's disable it for WMF (being a separate issue) and simply enable it by default for other users of MediaWiki.