Do you think Flash and Silverlight are any different? I'm still yet to even see anyone deploy Silverlight in a meaningful way outside of Microsoft and a very niche Microsoft-loving sites.
I think Silverlight has as much of a right to exist as Flash but honestly we should expect better than to have browsers needing third party plugins in order to deliver animation, video, webcams, and sounds.
Ah, but Silverlight does not require a browser to provide usefulness to users and developers... The future of OOB is quite compelling. Again, why does it have to be all or nothing? This is what I mean about a heterogeneous future.