If they feel the true future of their product is in streaming than I think this makes sense. They aren't trying to hold onto the low-margin DVD my mail people. They are trying to encourage more streaming customers and move forward in a drastic way.
Maybe the better way to accomplish this is to make the netflix classic website as discussed in the article include the non-streaming movies and just have people with instant queue not even see other movies.
Regardless- I don't think one queue is necessarily better.