There are two separate issues: what is legal and what is possible. The downloadable copies you're referring to are certainly available, but downloading them is illegal. For many people, that makes a difference. The post I replied to specifically asked what would happen if Netflix changed its terms from renting to buying. I assumed that this meant that Netflix subscribers would be able to legally and conveniently download as many movies as they like during the period of their subscription. I continue to believe that such an option would lead to spiral of bulk downloading and Netflix price increases, but it's not an option that exists anywhere, so it's hard to say.

Now, a different and more interesting question is what would happen if Netflix maintained the legal requirement to only view movies through streaming and not to store them, but eliminated the DRM. This would make their model comparable to Amazon's MP3 store, except with for video rentals rather music purchases. Netflix certainly think that such a model wouldn't work for them, and I'm willing to give them the benefit of the doubt. You can point to MP3 stores such as Amazon's to say it would work, but it's interesting that even though MP3 purchases are widely DRM-free, music streaming is still DRM-protected (as near as I can tell: correct me if I am wrong).