I am wondering if it's possible that the QLED Q90R could get a eARC via firmware update, some people have suggested this possibility but the Q90R tv doesn't have HDMI 2.1 which is necessary for eARC, this is a hardware limitation that can't be fixed via firmware updates. However there is a possibility Samsung makes a new One Connect box with a HDMI 2.1 port In the future, if this happen would this box work with the Q90R tv. If so I'll be more than happy to buy a new box if I can get and HDMI 2.1 port to get true Dolby Atmos from the tv.
There is a possibility of a firmware update due on the next few days. The update will be for both, the QLED Q90 Tv and the HWQ90R soundbar. This is supposed to provide eARC capabilities to both devices. I hope it happens soon.