A wireless access point is effectively a router. It can serve DHCP of it's own accord or it can pass it through etc. I have my wireless access point connected to my Virgin super hub and it's working perfectly. I have the wireless switched off on the super hub but still have wireless through the AP. The AP is connected to the router with a CAT5 cable. How could connecting any other router be any different? Providing the other router has an uplink port on it, I can't see any reason it wouldn't work. My superhub hasn't had a FW update, it is as supplied by Virgin 2 months ago.
I'm not a networking expert by any means and only know enough to manage my home setups, but it just doesn't make sense to me what you're saying.
Regards,
The firmware discussed will, as I understand it, enable the 'superhub' to operate purely as a modem, completely eliminating the router functionality..
According to Virgin when I asked, many months ago, about your solution they said there were circumstances in which it would not work. I vaguely remember being told that, e.g., PS3s used for online gaming would not work due to NAT issues.