Just to clear up the confusion regarding what Rundgren's No World Order
interactive disc allowed the user to do:
It was not designed to allow the user to remix in the sense of starting from
the raw material.  Instead Rundgren had already made multiple mixes of the
invididual songs, and the interface allowed the user to choose the type of
mix, or to string similar tempo songs together.  You can change events
during the playback of the disc.  It's more akin to creating an extended
dance mix out of elements already prepared.  The user is not able to
actually add or subtract any of the original components of the
music...although there is a "karaoke" mix included for those that wish to
blab their own rappage over Todd's grooves.  (Bleah.)

I think it would be possible utilizing DVD technology to create discs that
hold multi-track versions of songs, but someone would likely have to create
a software standard to run the format to make it more feasible in the
marketplace.  Not everyone will agree on which of the plethora of recording
programs available is most commonplace for potential users.  (For example, I
love ProTools, but there are equally vociferous users of other platforms.)

The question really is if there are enough people truly wanting the access
to such material to warrant the cost of developing the product...and then
the licensing of the desired recordings...and so on...and so on...

Brioohs