Umm how are they doing in units. The past few years the DVD market has become over saturated. Which means there's alot of quality movies/tv shows in bargain bins for rock bottom prices.
Also this is fairly predictible. Movie/Music companies get a huge boost after a format change. IE VHS to DVD or VINYL to CASSETTLE to CD. Most DVD diehards have probably built up their collections.
Now that they've priced dvd's so ridciously low. The price diff between dvd and blu can be huge. IE 7 bux for braveheart on dvd or 20 on bluray, which alot of people aren't willing to do.
If bluray doesn't become mainstream (and stays a niche product). I think thats it. It'll be all downhill from there.