I have a feeling that Blu-ray will be victorious. I am not a Blu-ray fanboy, nor a HD-DVD ditto, but Blu-ray has exclusive support from 3 major studios (Sony, Disney and its constituates, and Fox), whilst HD-DVD only has exclusive support from one major studio (Universal). Spielberg's films, Star Wars, Pirates of the Caribbean (Trilogy), Spiderman, and so many other top grossing films put Blu-ray in the spot light. And with movies like Lord of the Rings, Harry Potter, Matrix all being available on both formats at some point doesn't really affect either side in terms of winning the war.
People like to mention Sony's previous media format blunders such as Betamax and minidisc as if to indicate the demise of Blu-ray before the gates are open. The Blu-ray thing is well funded, and has lots of support. When Minidisc became available they didn't get massive amounts of support or external funding for it. The same can be said for UMD (Not sure it was intended to be used for much else other than the PSP) or betamax.
This is of course all speculation, and no one can be absolutely sure what will happen. But I do think that Blu-ray has the better ground.