I apologize, a few omitted words from my posting altered the statistics a little. But the bottom line is the same, the increase in rentals, video-on-demand & Blu-ray sales is not enough to cover the loss of DVD sales.
This impact is affecting more than just the home video market. For the past 25 years Hollywood has gotten used to relying on the sales of home video to justify the expense of producing the movies. If the studios can not find another way to make money on the secondary market, we could see a reduction in the financing of new movies.
On another note about the Double Feature DVD releases, this is to try to get sales on titles possibly overlooked by some of the buying public who did not want to spend much money on DVDs. Offer a 2-for-1 and you might be able to squeeze a few more dollars out of the buying public for that title. Actual production costs of the discs, once mastered, is quite small. So once the re-mastering costs are recouped, distributors can bring down the cost of the discs or sell double feature versions. The reduction in profit margin still means an increase in profit if the sales go up.
In some cases Sony (and other studios) offer multiple movie packages for first time title offerings . An example is the new Bad Girls of Film Noir DVD release. These are low production cost DVD releases and the studio feels that chances of good sales are increased by offering these multiple title sets up front.
DVD sales could always go back up when the economy improves. The non hi-tech customers who are happy with their DVDs performance may have money to spend again.
Would I buy a Blu-ray copy of a Monty Pyhton title? I doubt it, they shot much of their stuff on grainy film, it would not benefit from Blu-ray.