I work for a CD & DVD Duplication/Replication company, and part of what I do is research the latest trends in the industry. I may end up eating my words, but I am betting that Blu-ray will come out on top. A lot more news, studio support, and progress has been coming out of the Blu-ray camp.
To sum it up:
Blu-ray - Revolutionary
HD DVD - Evolutionary
I don't plan on replacing all the DVDs I currently have. Once one of the high-definition formats comes out as the winner and I eventually buy a player, I will simply add to my collection with the new format; the original DVD technology will be backward compatable.
Anybody who is interested in keeping up on the latest news with this, may be interested in the list of articles that I maintain:
http://www.discburn.com/newsletters/