" I would be curious what would happen at the consumer level if suddenly, no DVDs were available."
They would buy the PS3 or a Blu-Ray player and watch movie on Blu-Ray, but since that scenario cannot happen, the transition will be at the same pace DVD took over VHS most likely, or slightly slower.
Streaming is for the minority right now. We need next generation to completely take over if we want to see online content become the main market place for movies. The majority of current 25+ folks still feel attached to their physical content, be it DVD or Blu-Ray, or even music CDs.
Or it could be even something completely unforseen, like everyone going back to the theaters and dropping the whole "home movie entertainment" stuff.
We can't blame people for wanting to be able to feel with their hands whatever they buy. I mean... even a theater ticket you can feel it...