SilverLight == JS widget kits (Score 1)

Silverlight is not just a video streaming tech. It's a great client-side library that works great for business apps.

Currently, there is no JS widget kit (Dojo, et al) that provides the experience that SL can.

SL has a long life as an enterprise solution platform.

MS could even produce a version of SL that renders to the HTML5 canvas.