Hi Russ
To be honest, I think you are more "right" than I am in.......in that those with an Atmos processor will be able to play a 'regular' 5.1/7.1 BD and still achieve an Atmos experience, as the Processor will be able to simulate an Atmos type experience by adding height etc., to certain effects
And the "quality" of those effects will depend largely on the DSP included by the various manufacturers.........e.g. in your face by Yamaha and more nuanced and subtle from Denon & Marantz
And that is what you're saying above with current 2D Blurays being played back in "simulated 3d effect" by various players and TV's
Attached is a list of the Atmos
Cinema releases in 2014 and planned for 2015
Readers can look thru that list and count the number of titles that they would buy......or more particularly install an Atmos solution in their favourite viewing environment for
For me, Cliff says it best "one of the few Atmos releases of interest to those aged 7 or above"

And full disclosure, I've mentioned on here a few occasions that Gravity was one of the very rare 3D releases that I thought ADDED to the overall experience........and I can also say that the Atmos system installed in the Cinema I saw it in added greatly to the experience......but it must be said that Gravity was designed and engineered from day 1 as being an "enveloping 3d Audio and Video experience"......not the afterthought and post-processing conversions that most releases are
So I agree totally with Cliff........but there would need to be an awful lot more releases of the calibre and design of Gravity before I'd be remotely tempted down that path