I have TV and Internet services on Telus' network here in Canada (I think they use the same platform that AT&T uses, which is a Microsoft IPTV solution).
TV and Internet come through the same connection at my house as a shared pool of bandwidth. They are sold separately, and TV actually hinders Internet performance.
I have 25Mbps down, total (which is freeeaking awesome for the price, about $50/month). Each HDTV channel used consumes 5Mbps. So if we are watching two TVs, we'll see only 15Mbps remaining for other data services.
I have no issue with this, either in practice or in principle.
In practice, Telus backs up the bandwidth truck and unloads it at my house every month, and I can't consume it all.
In principle, the market will decide whether to support the model longer term.
I for one won't hesitate to turf the dedicated TV services if Internet services can equal it in terms of quality/availability/price. But until then, I'm happy.