As far as I recall, cable through Virgin is actually the biggest single way consumers get broadband in the UK. While more are getting it down their phone-line, Virgin have more subscribers than any other provider. Since they are about the only ones who don't provide a router with their modems, it is the most commonly asked for in our store. I guarantee you for every customer we have with ADSL wanting to buy a router, we have another with cable. Most of the ADSL ones also tend to be replacements as time goes on because more are providing them these days.
If Apple brought out a model with ADSL built in, it would be welcomed. If they brought out only this model, they would be incredibly stupid.