Well, I think the next jump is really to just get a season of a television show onto one HD-DVD/Blu Ray disc. I think we would be skipping a couple of steps in trying to get HD video onto one disc. A portable 300 gb holographic disc, though ideal, is going to be expensive when it comes out, and as exciting as it may be, it's going to take some time for the price to come down and for consumers to feel comfortable with it. From a marketing standpoint, Blu Ray and/or HD-DVD are a better bet for the near future. Also, blank HD-DVDs/Blu Rays should be a hit as people are always looking for more space to store their files, home made movies or what have you. I think the concern would be that while it would take the 4 or 5 years for holographic data storage to be fully developed and for prices to drop to a point where it would be a viable option, we'll still be using DVDs in the meantime.
I think that holographic technology should be explored more as a permananent replacement for HDDs, and then as that blooms, introduce removable holographic memory cards and the like.