Exactly the point I raised above. Probably more a matter of a return on the needed investment than anything else. I think sooner or later we'll see
Stupid Dream,
Lightbulb Sun,
In Absentia,
Deadwing,
Fear of a Blank Planet and
The Incident in Atmos. I'd bet money on this. They're all available in 5.1 already and between the above (can't believe that you can't replicate a working ProTools 1999 workstation today) and the continuing progress on AI, if there will be the will (this might be a big if, I don't know), the rest will come.
EDIT: somehow the forum's software made miss the last two comments before mine.
@minimumtumbleweed don't you think that with AI and the already existing 6 discrete channels available a talented engineer could manage to do a good job? Even though my main point of doubt remains on "can't work with old ProTools anymore".