As I already stated, Google could have made all their Youtube video content DRM encumbered ages ago with the flash plugin had they so wished, why would they suddenly do so now because of EME?
Content which already used DRM (through flash, silverlight etc) will continue doing so, nothing gained or lost here.
However, what we do gain is a standard way of serving non-DRM encumbered video which can be supported across all platforms. This is what I care about, whether or not commercial DRM laden content is distributed using separately installed plugins like flash, or if they are installed through a extension mechanism in the HTML5 standard really doesn't matter to me.
Commercial content will require DRM in order for it to be distributed, Hollywood won't have it any other way. If you want to consume that content you will have to bend to their will (or pirate it), again, in practice I don't see how it really matters if it's through externally installed plugins like flash, silverlight, or through an EME mechanism in the HTML5 spec.
And yes, Linux and other open systems will likely never get the kind of official support from Hollywood content providers as those systems where it's easier to lock the content pipeline (not that it has ever worked sofar, but you can bet they will keep trying...). It's just something we will have to live with.