At the latest PDC conference, only a very few mentions of Silverlight were observed. It seems that Microsoft is betting on HTML5 as the future for cross platform development.
They even claim that Silverlight is now a Windows Phone development toolkit (read this article from ZDNet).
So it is really safe to continue your developments on this platform ? The interest of Microsoft to buying Adobe is now more clear, as I think Adobe will be best positioned for generating HTML5 interfaces, mixing Flex and Dreamweaver experiences.