It might be possible to change the DRM modulation scheme so the receiver can use high fidelity when the signal is good but remain locked to the more robust signal when conditions are poor - from the same transmitted signal. The scheme adopted for satellite video transmission DVB-S2 allows for this (although I'm not aware of broadcasters using that aspect here)
However, anything added now should be backward compatible to existing gen-3
receivers, those who invested in DRM30 or DRM+ reception have been sidelined because of the introduction of xHE-AAC. I think that means only the Gospell and Titus can do DRM now. What about Diveemo?
Also take note what is happening with DAB in Britain: many new stations are starting up in DAB+ only, 32kbs mono. They are not interested in stereo because of the cost. FM analogue and even AMstereo (AMAX) now outperforms it in every aspect of quality. The BBC has to keep its main programmes on the DAB standard due to the millions of expensive car radios and home portables that arn't upgradeable (I have one)
The cellular operators like LTE because more streams over their network= more tariff because unlike broadcast, the listener pays for the transmission costs. LG are selling a DAB+ Android phone here and Australia with the advertised advantage of no data charges and better battery life for the user.
The two things I would like the gen-4 DRM release to include are - Diveemo support and Opus codec support.
The one thing I would like smartphones to have is DAB+,DRM+,AMAX on all bands 0.5 thru 240 MHz