The problem for cable companies is they lost the legal battles concerning remote DVR solutions. They HAVE to put a hard drive in your home to get the fair use protections on recorded televisions, but the Sat providers, at least, are already moving towards whole home server/thin client models. The DirecTV Genie DVRs now have really small HDMI sticks that are serviced from the tuner via wifi and Dish Network uses small "Joey" clients that can connect to the Hopper DVR via coax or Wifi. Dish also just released their PS3 "Joey" app which is just a software front end for the DVR that runs over the network. A PS4 version is also promised, and in theory Dish could make apps for Roku, FireTV, Android, iOS, etc.
One thing that is changing is the proliferation of "OnDemand" content, which is basically remote DVR under a different name. A true over the top IPTV service should just mandate complete and immediate OnDemand access for everything a channel broadcasts (at least for a window of so many weeks) so that users don't really need a DVR, local or remote. They can instead watch live or hit up OnDemand for things they missed, subscribing to their favorite shows to give them a feed of what's new instead of a list of what was recorded.
EDIT: PlayStation's VitaTV represents potentially a perfect nexus device by combining PlayStation Now, Remote Play, Netflix and Sony's rumored IPTV service.
I have Dishworld which I believe is thru Dish and it allows me to access content thru IP streaming that is archived by Dishworld although I'm not sure how far back or long its stored for. I pay ~10.00/month and it's a far better deal since the only thing I used to watch on TV was La Liga, Serei A and Champions League. We have Netflix so my kid loves everything she can access on from the Playstation, which my wife also loves but we still have a really basic satellite package so she can see live news. When the news channels come to IP (in some ways they already are) we'll be a satellite/cable free household. We were paying >120/month for 2 DVRs (one of which I own) and now we pay less than 40/m total for all 3 services and have access to much more content and with the ability to stream to smart phones and tablets much of what we want can be accessed remotely....