Personally, I find this wonderful. Microsoft should severely deprecate and eventually eliminate Silverlight. I find Silverlight much better than Flash, but at the same time, the need for proprietary solutions for content delivery has faded. Aside from DRM for Netflix, I fail to see exactly what Silverlight provides that cannot be actualized using the modern web "standards," such as HTML5.
By switching to "standard food" as opposed to their own dog food, Microsoft will encourage the use of their cloud services, and in turn will hopefully allow for better integration into the modern device ecosystem. SkyDrive shows promise, but it is not really useful. By switching to HTML 5, and if they allow it to become a locally mapped resource on devices it would be infinitely more useful. An HTML5 based solution could theoretically run on any system, local or mobile, and the switch makes sense for everyone.
Except for the developers who got onboard the Silverlight ship, that was showing holes and sinking on departure.