Some recent reports on the subjective performance of the Marantz AV20 & AV10 AVP's, (and possibly the Denon A1H AVR?) - seem to indicate improvements in the Atmos / Dolby Surround (and possibly other) decoders, with new owners reporting immediately noticeably improvements in immersion and effects when upgrading from previous generation equipment.
Nothing firm as to the cause yet - but it looks like Dolby have been doing work in the background on their decoding algorhythms, and the results are positive.
So there ARE improvements to be had, they are built into the firmware, and unlikely to be provided to older equipment (even though the older gear COULD technically be upgraded with firmware upgrades, but they won't...).
I expect these improvements will trickle down to more mass market gear, either as firmware updates to current models, or as an incremental improvement as new models get released.
Rave reviews by some owners of new AV10's seem to indicate there is good reason to look at an upgrade.
Fundamentally, we have moved from a hardware paradigm, to a software paradigm. But the marketplace has yet to catch up with this.
Dolby, DTS, Auro, are all continuing to released improvements/updates to their software. - This means it is no longer about having an AVR that supports Dolby/DTS/Auro, but what specific versions of Dolby / DTS and Auro is the AVR running, and whether the manufacturer will continue to keep the AVR's software current with regular firmware updates.
What we have not seen, is reviewer and manufacturers advertising the specific update version on the product, and manufacturers making commitments to keep their products "up to date" with the versions of the decoding software....
(all without even considering new formats!)