Netflix has made a bold move, but I believe it did so too early. Netflix has always known that a pure streaming model was its ultimate goal, physical DVDs were just a temporary measure until everyone had enough bandwidth to make streaming work - the name Netflix doesn't even really make much sense for shipping physical media. With this timing however Netflix jumped the gun and here's why.
I might not be in the majority, but now that I've got a big screen HDTV, a Blu-ray player, and 5.1 sound I want to watch movies in high definition with surround sound. Streaming just doesn't offer that yet! I might occasionally be willing to settle for lower quality when I want instant gratification, but not usually. Streaming will eventually have those qualities, but not now.
Eventually Netflix will have to ditch those customers who do not want to switch to an all streaming model, but this early in the game they're cutting ties to customers who might eventually be persuaded to stay with them and switch. Splitting the company into two pieces with no connection between the two doesn't give them the chance to convince me later. They should offer some limited streaming service to physical disc users so when the streaming catalog does get better and the quality sufficient that these customers will switch and stay with Netflix. Now the playing field is even so a competitor can have those customers when they do finally go streaming. Netflix didn't just make the split too early, they've burned the bridges with the customers they're spinning off.