The built-in ATSC tuner of the North American Beosystem 3 as well as the one in BV-7 and BV-9 already supports QAM: it can receive UNENCRYPTED digital cable channels (including standard definition and audio only channels). I have tested it on my own set.
To enable QAM reception, you have to set "Cable" instead of "Antenna" in the setup menu of the digital tuner (DTV).
Cable cards are another story: apparently this is a dying system since cable companies want to sell set top boxes that are more easily customizable to provide pay per view TV or other services. In Canada, no cable company supports cable cards. So perhaps B&O will never offer that possibility.
Sony TVs sold in Canada also only provide "clear QAM " (unencrypted) reception.
Regards,
Jean