You are right about that and that is why Universal, Dreamworks and Paramount need to get off their ass and release some A list content now!
The days of "supporting both formats" are over for most consumers. They know that this will soon be all blu. Why would someone want to buy more discs on a format that will in a few years not have sellable hardware to keep it spinning? Most of the HD DVD sales you're seeing lately are HD DVD collectors who are buying additional machines as back-up devices for their HD DVD library (software sales have slowed dramatically). Many of us did the same thing with laserdisc with DVD came along.
With only 30% of the movie market, Universal and Paramount can't keep HD DVD alive even if they release their best titles. And as long as they continue to push the perception that they're holding up HD DVD to the best that they can, HDM sales will be slow for everyone. They both know that the real profit is from the large-scale sales of HDM software they'll be selling a few years from now on blu. Now they are trying to figure out the most advantageous way of migrating to blu to make that happen with the least amount of negative fall-out from their HD DVD catalog still on store shelves.
If they pull the plug officially today, no one will buy the stock they have already released. If they keep releasing A-titles... then they drag this out and make the problem even worse for themselves when it's time to switch.
What you'll see are these two studios slowly and quietly weaning themselves from HD DVD by way of advertising and sales... similar to what Toshiba is doing with hardware. Then once they feel that the market has reached saturation and they can't recover any more costs, they'll flip to blu.
This process is being carefully worked out between them and Toshbia so that their collective interests are taken into account.