Two things about the Silverberg interview.
1- He was at a Blu-Ray press event.
2- The interview was one day before Warner's license for Blu-Ray expired.
Warner renewed it's license to use the Blu-Ray logo (FLLA) but this is all I could find about it's main license, the CPA (Content Participant Agreement). If I'm not mistaken the FLLA is needed to continue to put the BD logo on discs. The CPA is needed to produce new movies in the BD format.

So Warner was maybe still negotiating and Silverberg was just a tool in the process.

This article from TV Snob claims the exact opposite. Warner will go HD DVD exclusive:
[Link: tvsnob.com]

Whether the above article is right or the following article is right:
[Link: cdrinfo.com]

doesn't matter until it actually happens one way or the other.