This separation model may turn out to be a very good one or a very bad one. But if we choose it and stick with it, what will happen in 50 or 100 years when it's either broken or irrelevent? Remember, we got to where we are now by choosing models that made sense in the voice telco time and make no sense at all now.
This separation model has been proven in the UK with electrical utilities, gas utilities and railroads. Some serious mistakes were made in the railroad model but they are being remedied over time and the model is being adjusted. In the UK, you can buy your electricity from your gas company or your telephone company. Or you can get your home phone from your gas company. There is a regulated utility that builds, repairs and operates the infrastructure and last mile but they do not sell to consumers and business users. Go to the website http://www.uswitch.com and have a look at the "suppliers" under the various categories. The separation exists in its purest form with gas and electric suppliers but you will notice that there is a "broadband" category because from the consumer viewpoint, DSL internet access appears to be structured in the same way. I think that the UK model is the model of the future and I suspect that the BT Openreach separation is an attempt by regulators to move telecom into the same type of structure. You may find the background documents at this site to be of interest http://www.reform.co.uk/website/transport/thefutureofrail.aspx because they show how the complexities of the rail industry are adapted to this model. I can't imagine telecom to be any more complex than rail. --Michael Dillon P.S. I have no personal knowledge of BT Openreach other than what I can find via google.