ADSL Router Concept
ADSL modem(s) (also might be nice to have the chance to do Annex B for germany, as well/instead), an Ethernet switch, and some form of wifi (with free software support for AP mode, and hopefully decent mesh abilities as well). I suppose some way of segregating the ports on the switch would be good too.
Investigation of options
ADSL2+ Chip: Infineon PSB 50610 E
A quick search for "ADSL2+ PCI card" came up with a potentially suitable chip. Further investigation of that chip shows that it's used in a GPL-compliant Belkin ADSL2+ / 802.11N WIFI Router.
The only major piece of the missing puzzle, therefore, is how to get this PSB 50610 E connected to an EOMA-68 CPU card. USB? Ethernet? If Ethernet, that would mean having an on-board CPU, which probably means doing exactly the same circuit as already exists in the Belkin F5D8233!
Yes it does have an onboard CPU, it's running Linux in fact. See this link for further information http://tjworld.net/wiki/Linux/Embedded/Infineon/Danube/ADSL2PCI
People have tinkered with it a bit, but considering it's a 2006 chip, personally I wouldn't bother using it for new designs. It's its own device, as all ADSL2+ modems seem to be, and none of them are accessible in any way, nor do they meet minimum quality standards.