> I do wonder if in the longer term if Apple's Spatial Audio with "dynamic head tracking" isn't the next 3D TVs/3D Content i.e. a gimmick.

For what it's worth, I have a pair of Audeze headphones that has 3D head tracking or whatever they call it, and I don't think it's a gimmick.

When I'm wearing those and watching a movie on my TV (or playing a game on my PC), the sound really does appear to be coming from in front of me (or beside/behind me depending on the channel or the mix), and if I turn my head, the sound stays put.

It's somewhat subtle, but it can make me forget that I'm wearing headphones and I personally find it really adds to the experience.