Most HDTV shows are broadcast in 5.1 and I believe the format has the capacity for 7.1. All they would have to do is give you 8 stems instead of
their surround mix, which gives you no control. The technology is already there, but the people who have the ability to implement it would be making their own jobs obsolete if they did so.
The demand for this may be limited to ME
right now, but if it were made available, I think millions of people would love it.