Disclaimer: I did not read through the thread.
I would have guessed panel speakers were the dinosaurs, if anything. Panels must be much larger for the same output (at least until we get high-current room-temperature superconducting magnets), have that back wave to contend with, and are generally harder to set up than box speakers. HT and it's requirement for more speakers seems to lead to more, not fewer, box speaker systems. Couple that with arguably fewer people able to afford homes with large media rooms to provide space for a set of panels, and box speakers appear here (or, "hear") to stay...
It is also easier for the average speaker designer to grab conventional speakers and build a box than to design and manufacture a good panel speaker, IMO; where does one buy panels (planer magnetic or electrostatic)? The box also allows tuning and better control of driver extension, e.g. higher damping compared to a typical panel.
There has been some interesting research into generating sound by using small emitters and wave interference theory to create a "holographic" sound system with no conventional drivers. Perhaps that is the future.
All that said, I am not giving up my Maggies!
- Don