MS will surely want movie support in their next box.
Why ? I had both the DVD remote kit for the PS 2 and XBox last gen. Between them I used it maybe ten times. In the same time frame (last ten years) I went through three stand alone DVD players.
PS 3 made a difference because it was the best BluRay player for the buck (until recently it was the best player outright), and as you've mentioned helped Sony win the format war.
But in 2-3 years people will be paying $100 for decent standalone Bluray players and disc-based movie playback will have no real significance for a console.
Online movie rental is going to do the same to physical movie media as online music did to the CD format.
On top of that Microsoft doesn't have the vertical business model Sony has, they don't own studios, distribution etc. They only have the end users, so the don't have the same incentive to push movie support the way Sony do.
I live in Denmark, and I would *love* to have NetFlix or something similar. I have rented everything worth watching on Zune, but it has two downsides: 1.) lack of titles (both new and back catalogue). 2.) lack of regionalization (subtitles).
My physical media player could then be relegated to playing the odd SACD that can't be replayed on anything else.
Now, some people will need a physical media, because they don't have access to the required internet connection, but a whole bunch of people don't. I could imagine two SKUs, one with a Bluray drive and 16 GB flash and one with just a 500GB 2½" drive.
What DD need to take off, is significantly lower prices than physical media. As long as I can buy games at 50-60% full price just three months after release. As well as take my games to my brothers house to play with my nephew, there is little incentive to buy it online.
Lower prices and a Steam like gift-a-game rebate (could be time-limitedI) would make it much more paletable.
Cheers