HD-DVD is just an additional revenue stream, and will be treated as such for 5-10 years - if not longer.
98% of sales were on DVD - 2% on HD-DVD. All this means, is they managed to squeeze a premium purchase (think "special box set") out of 2% of the consumers that bought the movie.
DVD is still by far the most important format - 95% of their revenue came in via DVD sales.
...
The same will happen with BluRay. Do you think Sony will delay or hold back the DVD release of Spiderman? I think not - they want their 95% of revenue, just like any sane company would.
Its also hard to measure these sales fairly IMO. Transformers was a "bonus" when buying some HD-DVD players? Spiderman will be the same, and a pack-in for PS3 purchases?