It would make some sense to let the 978 be 7.1 no matter what ends up happening with the 998. That places the 978 in direct competition with the AV7005 (7.1 DAC's and Audyssey) - the 978 would have a few less features (mostly related to network functions) but could have a better analog section and will likely have either the same or a better Audyssey suite. Plus if the 998 did end up with any extra DAC channels (probably just 9.1 at most for PLIIz support), it would offer a little extra differentiation between the two models.

The one thing that is curious about the 9.1 and 11.1 DAC support is the lack of single-chip DAC solutions for it. Manufacturers have largely settled into using these eight-channel DAC chips for both players and receivers, but to go beyond that they have to pair them with separate stereo DAC's. It can be done, of course - just as was once done when pairing six-channel DACs with stereo DACs for 7.1 support in both receivers and some players - but the scarcity of homes that will actually have nine or eleven speakers connected has probably helped companies justify leaving the extra hardware out.