The broadband money tree is about control of your Internet experience as much as it is about new revenue. Along with content you ask for, there will be some additional content added. The premise here is that things are easier for everyone if they are done online. Lock-in works best when users don't have choice. Not as much as you think.
Cable is generally less.
Add a couple of books and magazine subscriptions, and that's it. Basically, if there's a lot of compelling content on the Internet, people will buy it, but they will give up something else in exchange. In the beginning there is more spending while users explore their options, but over time this will taper off as the novelty does. Online services are new revenue because the profit they generate comes from sources that typically would go to more traditional businesses. I'll use my family as an example.