I agree that it's pretty much over. IMHO, having Disney in the BR-exclusive camp gave them a big advantage to begin with. Coupled with the PS3 BR "Trojan Horse" effect, it really never projected to be an HD DVD world for next-gen HDM. Losing Paramount was a minor hit, but it was only delaying the inevitable. The Warner move simply pushes the HD DVD demise forward.
Warner actually pushed the idea of HD DVD/Blu-Ray combo discs at last year's CES. No one else bit, and here's where we're at- with the largest seller of DVD and HD abandoning a format they previously thought could help.
Retailers have been helpful as well. When I walk into a Sam's Club or a Target, I see Blu-Ray endcaps. When I walk into a Best Buy, I see Blu-Ray demo and browsers talking about Blu-Ray. Even during last week's buy-3-get-2-free HD-DVD sale, I was next to an HD DVD player owner while searching for movies worth buying. Neither of us could find those five so we left without purchasing anything other than a single Blu Ray title (RE: Extinction). And with Warner gone, it's only going to get worse.