In the Taiwanese Market, sales of DVD burners has surpassed those of DVD-ROM/CDRW combo drives. Combo drives now have less than 50% of the Taiwanese market. Interestingly Sony's drives have gone from having a 50/50 Combo drive/DVD burner split to 15/85.
Digi Times reports that the reason for this is the seemingly frozen price of combo drives, coupled with the ever decreasing price of a DVD burner.
Of course, we have the fun of high capacity DVD burners to come, but until then it looks as though people are snapping up 'classic' DVD burners. You're less and less likely to see a DVD-ROM/CDRW combo drive in a PC for sale now, unless it's a real cost-cutter.