Is there anyone else who does need this? I would find it awesome and very helpful. You wouldn’t have to buy a second device (cable modem) to get on the internet. In addition, this may be a safety hazard, as the cable modem could have been attacked before the router even notices it. Possibly returning incorrect IP addresses for DNS requests that the router requests through the cable modem (gateway).
This would be cool. However, I think the problems with DOCSIS are even harder to crack than the VDSL.