The biggest advantages to moving from a third party RIA framework to Silverlight is that it is a fully supported framework. It is a technology Microsoft are pushing at full force to achieve market supremacy and that it has full integration with .NET
Silverlight is based on the .NET framework meaning that integration with .NET applications is a simple matter. With a web service on the backend to feed the Silverlight control, extraordinary feats of usability and functionality can be developed to meet any and all business requirements.
For the people afraid of the user base of Silverlight not being high enough to implement a solution in it, firstly the technology is rapidly growing every week, the number of users adopting the technology is also greatly on the rise. Silverlight offers a very fluid “graceful degredation” to another technology of the developer or companies choice for those who don’t have the Silverlight plugin installed.
Silverlight is aimed at two groups for development, firstly the creative teams add the animation, graphics and effects using “Microsoft Blend” as a creative tool and the backend developers create the functionality and integrations using “Visual Studio”, Microsoft have created blend with the idea that the Silverlight solutions can be loaded in blend or VS independently and can share the same solutions so both developers and creatives can work on the same solutions.
SharePoint and Silverlight.
With the release of the new versions of SharePoint 2010 and Silverlight 4, it is now possible in Silverlight to display and manipulate SharePoint information and functionality without relying on external connections to webservices so much. New advances have been made to Silverlight with the inclusion of a “Silverlight Client OM assembly” this effectively allows developers to directly integrate their applications into SharePoint.
SharePoint development in the years to come will be very Silverlight oriented and solutions based on SP2010 will increasingly provide Silverlight interfaces as users want the slickest integration they can get and gold partners are willing to provide it!