Way back when I built an internal site for a customer using silverlight 2. They've been happy with it and I've barely had to touch it. Is the expectation that this site will always work? What I'm afraid of is suddenly getting a call years from now that the users installed silverlight X and now it's broken and I'm going to have to convert it immediately past Y versions of Silverlight to get the site back up, and I don't even do Silverlight anymore. I already went through this once when it went from 2 beta to 2 release and and scrambling to fix all the breaking changes and get the site back up. It wasn't as big a deal then as we were in beta anyway. I could upgrade now but it would be really tough to go back to the customer and ask for money to do an upgrade when they are happy now and will see no noticeable benefit from staying current. Additionally there are some third party controls that would have to be licensed again. So I guess what I'm asking is there a known end of life? Or do we just play it by ear?