"By 2012, standard DVD discs will total $10 billion in U.S. consumer sales, HD DVD $5 billion and Blu-ray $5 billion," per Adams Media Research, as reported by Video Business.
This compares with 2006, in which DVD was a $16.5 billion business, according to the Entertainment Merchants Association trade org. (Unclear if this also includes hi def, but the difference is probably not great either way.)
That growth, even in the face of the continued hi def format war (Blu-ray vs. HD DVD), means that the WGA's failure to achieve an increase in the DVD residual (see WGA Strike - Negotiation Issues) will continue to represent a significant loss, as I previously predicted. See Slipped Disc: Why DVD Residuals Still Matter — and Always Will.