Way back when, you had to rent equipment from the Phone Company. You could get any phone you wanted so long it was in one of their 2-3 lines and 6 or so colors. Not much choice.
Then, they opened it up so that you could buy equipment. It really opened up the answering machine business. It also created much more choice. You could also continue to rent from the Phone Company.
I think cable should be the same. Set up a standard and allow people to buy or rent equipment from whoever they want.
I am aware of Tru2Way. It is close but not a complete solution. I think it leaves too much in the control of the Cable Company. I would like to see Sony and Panasonic and other companies provide their own interfaces - like Tivo does. With Tru2Way, most of the interface and all applications will be delivered from the head end. It is kind of like the way Verizon controls cell phones with the GetItNow feature.