I am tempted to think that maybe the DVD business should have been called Mailflix or Flix by Mail or Next-day Flix.
Granted, Qwikster will still stay around for a while, but I have no doubt that it will slowly die, just like Blockbuster right now.
Blockbuster dies rather quickly mostly because of Netflix. So, in order to predict DVD by mail business dying you have to show the alternative. Streaming currently is by no means a match. One could see Redbox putting more advanced kiosks with more selections (there was talk about kiosks with thousands of titles that would burn the DVD while you shopped) which might be threat.